Neighbor: "Hi, Tom! Long time no see!"
Tom: "Hey! I know, it's been ages. How have you been?"
Neighbor: "Pretty good, thanks. Anyway, I've got to run. Take care!"

"Long time no see" is a classic, fixed idiom used when you haven't seen someone in a while.

"How have you been?" is the present perfect tense, naturally used to ask about someone's life since the last time you saw them.

"Take care" is a very common and polite way to say goodbye. (While "Stay safe" is also correct, "Take safe" is not a valid expression!)