I'm sure there will be some differing opinions out there on this one, but for me personally, one of the things that I have seen really stunt learners' development of gaining a deep and broad facility in Thai (and other languages) has derived from asking 'How do you say [WORD / PHRASE]?'

COMPREHENSIBLE INPUT

It's broadly accepted in language learning circles that comprehensible input is the way to go if we really want to learn a language well. Sometimes starting to speak TOO much, TOO early can stunt us in the long run and cause us to develop some bad habits in the language. It's only natural that we want to know 'How to say' stuff - but how we go about learning 'how to say' it can make a world of difference.

Try this Experiment - 'How do you say "I Don't Understand"?'

If you're learning Thai, go and ask a native Thai speaker (who speaks some degree of English) in English:

"How do you say 'I don't understand'?"

Chances are they will tell you:
ผม / ดิฉัน ไม่เข้าใจ
phǒm / dichán mâi khâo jai

Is what they told you wrong?
*Absolutely not. *

Is how the concept of 'not understanding' is communicated in the wild in Thai?
*Sometimes ... but there are many other ways. *

E.g.

ไม่รู้เรื่อง
mâi rúu rʉ̂ang
Think of เรื่อง rʉ̂ang here meaning a 'topic' or 'plot' in the English idiom 'He's lost the plot' or what ever 'it' is in 'he doesn't get it'.

So, the meaning of ไม่รู้เรื่อง mâi rúu rʉ̂ang could be loosely used to mean:

to not understand

to lose the plot

to not have a clue

to be oblivious to something

even to not be able to do something in some circumstances.

If someone listened to something and then continued to display that they actually didn't understand what they had to do, they might swap out รู้ rúu (to know) for

ได้ dâi - to acqure / obtain / get

ไม่ได้เรื่อง mâi dâi rʉ̂ang:

To have not understood something even after it was explained

To not be able to hear something properly resulting in not understanding what's needed.

Adding Action to 'Not Understanding'

It's very natural in normal Thai speech to add a verb to the beginning which describes the 'action' of 'not understanding'

E.g.
** ฟัง / อ่าน ไม่รู้เรื่อง **
fang (listen) / àan (read) mâi rúu rʉ̂ang
To not understand what you're listening to (hearing) / reading

You could also use the same phrase to say
"This guy doesn't know what he's talking about"
คนนี้พูดไม่รู้เรื่อง
khon níi phûut mâi rúu rʉ̂ang

Not understanding Jokes

In English it'd be normal to say 'He doesn't get the joke' - meaning 'He doesn't understand the joke'. In Thai, to not understand the joke can actually just use the Tinglish word for **'get' เก็ท **
ไม่เก็ท
mâi gét
'to not get it'

This can also be used in broader situations outside of jokes if you don't understand something that's going on.

The Understanding ออก ɔ̀ɔk

Another common way to communicate 'understanding' in everyday Thai speech depending on the circumstance is using the word ออก ɔ̀ɔk

While the first meaning you might learn for ออก ɔ̀ɔk is 'exit' or to 'go out', think of it in this sense as a kind of 'being enlightened' to the meaning of something after using one of your senses:

**ฟังออก / ฟังไม่ออก **
fang ɔ̀ɔk / fang mâi ɔ̀ɔk
understand (make sense) of what is heard / Not understand what is heard

ดูออก / ดูไม่ออก
duu ɔ̀ɔk / duu mâi ɔ̀ɔk
understand (make sense) of what is seen / Not understand what is seen

This might be used when looking at art and not 'getting' or 'understanding' the message.

Back to 'How Do You Say?'

Getting back to the 'How do you say' issue -

If you ask a Thai 'How do you say 'I don't understand'?', it's only natural for them to respond
**ผมไม่เข้าใจ **
phǒm mâi khâo jai

It would be crazy for anyone to go into all the different nuances of how you'd say to not understand in Thai - and it's easier just to translate word for word. In most cases, that'll do the trick. ..and of course there are many more ways of expressing not understanding to what I've mentioned here.

As long as learners are aware that native speakers will generally give a 'general' response when you ask them - and sometimes they might not appreciate the nuance of the sentence you're asking in English, there might be 'meta meanings' in the response that they give you that you aren't aware of that could be problematic if you go and use it in every instance that you'd use what you thought the equivalent was in English.

Some people will even go so far as to filter out other versions of how to say that in the future, as they're convinced that the only way to say it is 'x' because a native speaker told them. Don't be that learner.

Eliciting meanings rather than Asking How to Say

I've noticed that especially with Embassy employees that I've worked with over the years, they will tend to fall into the 'Learn the language to be understood' camp (if they're not analysts). They learn the language that they need to do their jobs and communicate policy etc. to locals that they need to work with. They might develop a high degree of fluency, but it has a certain 'flavour'. Many have subsequently worked hard to lose that flavour once on the ground here.

Learning from native, comprehensible, natural input is very powerful, and while it might take a lot more effort to elicit how native speakers respond to something in a given situation rather than just asking 'How do you say 'X'?', the ultimate result is that you will develop a much broader, more natural version of the language