Hambi is an acronym standing for:
H - Humble
A - Adorable
M - Mature
B - Blissful
I - Intelligent
(rough translation)
It is mostly used in a small part of eastern europe to refer to someone close to you.
Some view being called hambi as the highest honor anyone could give.
Similar to "Best friend", and "Favourite person".
Person1 - Do you know Anna?
Person2 - Of course i do, she is my Hambi!