Many possible answers to this one but a good starting point would be either the belt is loose or you need to add Power Steering fluid to the unit itself.It could also have a bad bearing in it.
Power steering fluid maybe low check your power steering pump.
Failure in the power steering system...
Alternator Belt has snapped, causing you alternator to stop charging causing you battery light to come on, but this belt also runs your power steering pump which if that's not working your steering will become heavy
It means "electromechanical power steering." They put a little electric motor in the steering system that comes on when steering assist is needed, turns off when you don't need assist, and requires no power steering fluid. If the EPS light on your dash is on, it means this system isn't working.
It may mean your power steering fluid is low, or needs serviced.
Power steering fluid is low, or sensor fault
The dashboard light which looks like a steering wheel with an exclamation point beside it is the power steering light. If this light comes on, it either means the vehicle's power steering fluid levels are low or that there is a fault in the engine management system. When the light turns on, the fluid levels need to be checked first, and topped off if they are low. If the light remains on and the fluid is full, or should come on again when the driver returns to the road, then the vehicle should be inspected by a mechanic.
This means you have a fault with your power steering. You should contact the garage as the power steering may fail.
Electronic Power Steering (eps)
your power stearing fluid is low or the power steering system is bad.
It indicates a problem with your power steering system. Could be as simple as low power steering fluid level.
It means theres a fault with the electronic power steering. DO NOT ignore as it can fail at any moment leaving your car with no steering!!!