Bluetooth is a wireless protocol that's meant to be used for short range (say within a medium sized room to make it easy to understand) wireless connections. Things like headphones, printers, and other computer accessories.
So it can do a lot of different things, and it depends on what you want to do.
If your phone supports it you can sync your phone contacts with your laptop.
You can get bluetooth headphones and listen to and control your music wirelessly from your headphones.
There are a lot of other uses for bluetooth, but unless you have other bluetooth devices there's really nothing you can use it for. Think of it like a wireless USB plug.