Thank you in French is simply: MERCI. Of course, we have a lot of different ways to say thank you in French, just like in English and other languages. I will write a post about this subject very soon!
Let's look at the pronunciation
MERCI follows 2 simple rules of French pronunciation.
Merci = E is pronounced like È because it's followed by 2 consonants
Merci = C is pronounced like S because it's followed by the letter I.
If we look at the pronunciation with the IPA we have /mɛrsi/.
If you need help with your pronunciation, check out my playlist with 55 lessons to learn everything about French pronunciation.
Watch the video to make sure to pronounce MERCI correctly.