"Merhaba demek bile bir hizmet."

just a constructed phrase

Perhaps not--it's very similar to an Arabic saying, based on the teachings of a very wise man, "Even a smile is charity." It comes from a context where the concept of "charity" isn't limited to sending a donation, but includes removing broken glass from the public path, offering an arm to a blind person, giving directions to someone lost, or passing the kleenex box to dry fresh tears as well!

It refers to "Merhaba demek". Take a look at my breakdown below.