Hi, pretty generic reply here but some things to go on with.
Make sure the engine oil is the right grade & weight for the engine.
Be sure the oil filter is clean.
For those above a mini-service would be the easiest way.
If no change, find & replace the oil pressure sender unit, probably mounted somewhere on or near to the oil pump.
Would be useful to know the engine, mileage, service history & when the oil light flashes (from cold, when hot, after a long run...)
Any nasty noises from the motor when the oil light flashes?