It's kind of hard to explain how widespread a usage like "solvent" is. A huge amount of chemical reactions are most convenient to do in a liquid, a liquid that can dissolve the materials you're working with. That's a solvent. Benzene can dissolve a lot of things, including some that are really hard to dissolve otherwise. So it can be used for a huge variety of reactions, but as the sort background player that you might not pay attention to unless you can't have it.

It's a little like asking "what are the uses of water in chemistry", where you're tempted to answer, "um, everything?" Not quite, but not that far off either. (And with more cancer of course.)

Edit: disclaimer, I'm not a chemist, just an interested layman.