Cheek kissing is another common type of greeting in most French-speaking countries. However, the rules for cheek kisses can be complicated matter. The rules change depending on the country you're in and even the region of the country. For example, in Belgium, it's customary to greet everyone in your generation or younger with one kiss, but anyone that's a generation or more older than you should be given three kiss (right cheek-left-then right again). In Paris, most people stick to a four-kiss rule, but in most of the rest of France, two kisses is the norm.
If you think that's confusing, you're right. The good news is that when you meet someone for the first time, you can usually just shake hands. Then just watch how other people interact. Because it's such a common practice, you should quickly be able to determine what the standard is where you're staying.