What does Kolay gelsin mean?

Is this some kind of greeting?

The literal meaning of ´kolay gelsin´ is may/let it come easy.

It is not a greeting, but generally said to someone who is working (either physically or mentally)

It means may your work pass easily. It is often said said to shopkeepers, cooks, farmers, labourers, or anyone you see working.

Aha, that makes sense! No wonder they always say this in the market. Thanks!

Kolay gelsin – May it come to you easily.

If you hear someone is about to start a tough job or see someone working, this is an appropriate phrase to say. It’s also a very polite way to start a conversation with a service employee (for example, over the phone or after waiting in a line). I’ve found that service workers really will treat you nicer if you begin this way. It’s also a kind thing to say when you see someone working very hard in general.