“Γεια χαρά” is a friendly greeting in Greek, used in the same way as the greeting “γεια”.
It is translated “hi”. It gives a more friendly tone in our speech than just the word “γεια”.
-Γεια χαρά, τι κάνεις; = Hi, how are you doing?
-Καλά. Εσύ; = Fine. You?
-Γεια! = Hi!
-Γεια χαρά! = Hi! ( The answer is more friendly )
The word “χαρά” on its own means “joy, happiness”. The word “γεια” comes from “υγεία”, which means “health”. So, the combination “γεια χαρά” literally means “I wish you health and joy”.
The phrase “μια χαρά”, which Ιάκοβος mentioned, means “ok, fine, just fine” and it is used as an answer to the question “τι κάνεις;” or “πώς είσαι;”. So “μια χαρά” and “γεια χαρά” are not synonymes and they are not used in the same way.
-Τι κάνεις; = How are you doing?
-Μια χαρά. = Just fine.