French softens by changing the verb: je voudrais instead of je veux, pourriez-vous instead of pouvez-vous. The politeness lives inside the grammar of the sentence, and once the verb form is chosen the work is done.
Thai has no verb form to change. So the softening moves to the edges, and it is built out of small separate pieces that you add on.
- ขอน้ำkʰɔ̌ː náːm
water
grammatical, and closer to an order than a request
- ขอน้ำหน่อยkʰɔ̌ː náːm nɔ̀j
could I have some water
หน่อย is the softener
- ขอน้ำหน่อยครับkʰɔ̌ː náːm nɔ̀j kʰráp
the full polite request
Why this catches French speakers specifically
Having got the syntax right, you feel finished. In French you would be. A grammatically perfect Thai sentence with no particle on it is not neutral, though: it is blunt, and it is the standard register of foreign Thai for exactly this reason.
You are finished when the ending is right, not when the clause is.
นะ, if you only take one
นะ says roughly 'I am with you on this'. It takes the edge off an instruction, a refusal, a correction and a piece of bad news, and it costs one syllable.
It is not a politeness marker and it does not replace ครับ or ค่ะ. It works alongside them, and week 19 is about the order they go in.
- ไม่ไปนะmâj paj ná
I'm not going, all right?
- ช่วยหน่อยนะtɕʰûːaj nɔ̀j ná
give me a hand, would you