"Καλησπέρα! Τι κάνεις;"
Translation:Good evening! How are you?
It's καλή + σπέρα, not καλ + ησπέρα. Though σπέρα isn't used alone nowadays as far as I know (replaced by βράδυ).
It's shortened from the Ancient Greek form εσπέρα, which had rough breathing (hespera).
EtymOnline says ( http://www.etymonline.com/index.php?term=vesper ) that the Latin word is indeed related to the Greek one.
So what exactly does τι κάνεις; mean? Like the individual words and so on
Literally: "what do you do?" or "what are you doing?".
τι = what
κάνεις = you do, you are doing
But as a phrase, τι κάνεις; means "how are you?" -- it doesn't ask what you are doing right now but inquires after your health and general circumstances.