Saying "thank you" is a polite way to express gratitude to someone, no matter what language in which it's spoken. The following list describes written by writers from buyessayclub for the most accurate way of communicating this phrase in French.

The French Word for Thank You
The first step of saying "thank you" in French is knowing what the word is and how to say it. The French word for "thank you" is "merci." The correct way to pronounce merci is me(AIR)see. For example, if you were to thank someone for their help, you would say "merci pour votre aide."

Pacing
An important thing to remember when saying a new word or phrase, particularly if it's in French, is the pacing. French words are generally spoken at a quicker pace than English words. This is not to say that you should spit out merci as fast as you can or to slowly pronounce each syllable, but to find a balance between these two speeds.

Roll the "R"
You've already touched upon how to properly pronounce merci, but there is another detail in the way the word is said that makes all the difference. In the French language, the letter "r" is rolled. In order to correctly roll the "r" in merci, you must enunciate the "r" in the back of your throat.

Optional: Thank you Very Much
If you're feeling especially appreciative, you can say "thank you very much." To do this, add the French word for "very much," which is "beaucoup," onto merci. So, the completed phrase would become merci beaucoup. This is pronounced me(AIR)see b(OH)-coo.
In review, knowing the pronunciation, correcting the pacing and effectively rolling the "r" is the way to insure that merci is spoken correctly. Follow these steps, and effectively communicate "thank you" in the French language. "Merci" for reading, and don't forget to practice!