"Diolch" or "Diolch yn fawr".
assitant
"Diolch yn fawr" or "Diolch yn fawr" if you're talking to a young person.
assistant
Can you help me learn some basic words in Welsh?
user
Sure. What do you want to know?
assistant
How would I say "Hello" in Welsh?
user
"Helo" or "Helo chwarae" would be more formal, but "Helo" or "Dydd hi diw" would be more conversational.
assistant
What about "thank you"?
user