I have a 94 Toyota Marino. There is an indicator that is on the fuel side. It is orange and is a car with 3 lines coming out of both sides of the rear corners, like where the lights are. What is it for/ the meaning of it?

Possibilities.

Traction active. Remember to turn off traction control in rain and snow. I know, a misnomer. Traction control allows the wheels to rotate at different speeds. Cornering at high speeds. The lines are not straight.

Door ajar is another possibility.

Rear lamp out is my best guess. Could be any one of them.

Lamp failure indicator. You have either a brake bulb or a tail lamp bulb out.
The center stop lamp bulb is most common and has to be a 18W bulb so the lamp failure sensor reads it right.