Possibly coming from a leaking brake cylinder. Top up fluid and take to a brake shop ASAP.
Well, the engine in a 1974 vw Beetle is in the back of the car. So the brake fluid in front or the back to the left of the right.
the brake fluid reservoir is in top left hand corner below the windscreen.
For amount check the brake fluid reservoir. For amount of life left in brake fluid, use a brake fluid tester found at the automotive stores (Autozone, Advance, NAPA).
Depending on the vehicle, under the hood there is a container that is labeled Brake Fluid. That is where a person measures the amount of brake fluid left, and with a funnel adds the appropriate amount.
low brake fluid
Assuming you have disc brakes, it could be, a sticky or stuck brake caliper on the left side brake. Grease or brake fluid on the friction surface on the left side brake. A restricted brake hose/line on the left side brake. Air in the hydraulic lines on the left side brake.
the brake fluid reservoir is at the back of the engine bay, to get to it you need to remove the large trim that covers the entire width of the car underneath the windscreen wiper control arms. once this is off you will see the resivoir at the back left of the bay.
Be sure the cap is on tight, brake fluid absorbs moisture quickly if the container is left open.
I have noticed that if the brake fluid is low enough in the brake fluid master cylinder it will cause the light to come on when turning left. before it comes on for a low fluid problem because of the fluid shifting.
You can use a C-clamp to compress the caliper on just about any vehicle. You might want to place some rags near the Brake Master cylinder because brake fluid will travel back into it from what is left over in the brake lines. If you don't, you will spill brake fluid onto the floor.
Remove the black plastic cover (left side only) that covers the brake booster and brake fluid container, located between the left strut tower and left wiper blade (you will need T-20 screw head).
It depends on the type of fluid and level of contamination or heat. if there is no problem with the fluid it should be left alone!