if some has never heard the word “love”, does that mean that the he never could fall in love?

Of course he could! Love is a feeling. You don't have to put it to words to feel it! The word is there only to describe a feeling; the feeling was always there!!

well, same as if someone has never heard the word "hungry", would they never feel hungry?

The feeling of love is natural and all living things have it.

No. They would still have the feelings of love, just not know what it is and what it's called.

Yes, of course he can, but I seriously doubt someone wouldn't know what the word is love is, no matter what language it's in.

Unless he's a feral boy raised by wolves. But even there there's probably a gesture that is the equivalent of the word for "love," like not being bitten or something.

Some what?