Burned out bulb Faulty socket and/or wiring/ ground Faulty turn signal flasher Faulty turn signal Switch
That's the point. So people behind you know you are turning.
You may have a "ground loop" problem on the left turn signal. Check the ground wire at the front and rear signal bulbs.
Turn signal indicators are lights. The flash to tell you, or indicate, that a turn signal is on, and which way the lights are flashing.
First check the fuse if none of the lights even come on. If the lights come on but do not flash then the flasher relay is defective and needs replacing. If the fuse, light bulbs, and flasher relay are good then the turn signal switch may be the problem.
Replace the turn signal flasher relay.
Bad ground.
Check the fuses
If you mean that the arrow inside the dash turns on and stays on then your problem is one of the left side turn signal bulbs. Test by turning on your four way (hazard) lights and observing all lights. The one that does not flash is the bulb that needs replacing.
Usually a bad turn signal flasher
A strobe signal is the name for any signal that flashes on and off. For example the turn-lights on a car. Certain lights such as some leds aren't actually on all the time but flash faster than the eye can see, that is also a strobe signal.
If neither signal light works, the flasher may very likely be the problem. The hazard lights and the signal lights work off different flashers.
Flasher relay is defective.