If your brake system warning light comes on, it means there is a problem with your brakes. There are two main reasons for this:
1. Low Brake Fluid Level: If your brake fluid level is low, it means there is not enough fluid in the system to create the necessary pressure to engage the brakes. This can be due to a leak in the system, or simply because the pads have worn down and need to be replaced. Either way, you will need to add more fluid to the system before you can use the brakes again.
2. Air in the Lines: Another reason for a brake system warning light is if there is air in the lines. This can happen if you have recently had your brakes serviced and air has gotten into the lines during bleeding. It can also happen if there is a leak somewhere in the system that is allowing air to get into the lines. Either way, this needs to be fixed before you can use your brakes again since air will not compress like brake fluid does, and thus will not provide enough pressure to engage the brakes properly.