"Không có gì, tạm biệt!"
Translation:You are welcome, goodbye!
In context it means "you're welcome". If you're looking for a somewhat more direct translation to better understand it, it would mean "it's nothing". Kinda like "Oh no problem! It's nothing!". That phrase along with "không có chi" are the two ways I say "you're welcome" while growing up. I use "chi" when I'm being informal and "gì" when I wanna be a little more formal. Hope that helps?