Learn French: Vous devriez faire la bise à cet ami. - You should greet this friend with a kiss on the cheek.

Devriez is the conditional form of the verb devoir (must/to have to). While vous devez means "you must" or "you have to" (a strong obligation), using the conditional vous devriez softens it to "you should" or "you ought to." It is the standard way to give advice in French.

What exactly does faire la bise mean?

Faire la bise is the everyday French expression for greeting someone by kissing them on the cheeks. It literally means "to do the kiss." The English translation adds "greet with a kiss on the cheek" to capture the full meaning, since we don't have a single direct equivalent verb in English!

Why do we need the word à before cet ami?

In French, the expression is always faire la bise à someone. You are literally "doing the kiss TO" someone. Because the expression requires that à, you say faire la bise à cet ami.

Why is it cet ami instead of ce ami?

Ce means "this" or "that" for masculine words. However, because ami starts with a vowel, saying ce ami would cause two vowel sounds to clash. French changes it to cet to make it flow smoothly, so it becomes cet ami (this friend). If the friend were female, you would use the feminine form cette amie.