Ok, this is strange, the brake light will come on when driving on the highway for some reason. It will not come on in when driving through town. I made sure that the emergency brake wasn’t on, but for some reason I can’t figure this out.
Read your owner’s manual. It will explain that the brake warning light comes on if your parking brake is on or if your brake fluid level is low.
Your brake fluid level is marginally low. Add some and the light will go off.
You need to check to see if you have a brake fluid leak or if your pads are worn down and need to be replaced. One or both of those will be true.
Tardis has summed it up very clearly.
The OP needs to start reading that Owner’s Manual, even if it is over a decade late.
Here’s a theory, don’t know if it holds water. One or more of your brakes is sticking or hung up. On a highway drive it overheats, which causes the brake fluid to boil so the light comes on. You can look at your disks and drums and see if one looks a lot different from the others (heat damage).
Otherwise, I’m not sure why, if the fluid was simply low, the light would only come on during highway drives. But check the brake fluid anyway, it’s an easy fix if that’s the problem.