An engines oil pressure reading should be a minimum of between 25 PSI to 65 PSI.
When you first start the engine the engine oil pressure should be around 60 PSI to 65 PSI but sometimes it may be a little lower than that and it's okay if it is.
But as your engine warms up your engine oil pressure can naturally drop because as the engine oil warms up the oil gets thinner which creates less pressure.
So you might see the oil pressure drop to 40 PSI or even as low as 20 to 25 PSI.
My engine oil pressure in my truck is at 60 PSI when I first start the engine but after I drive for around 20 minutes and the engine heats the oil up the oil pressure actually drops to around 5 PSI which is not great but it's still in the safe zone.
As engine bearings get miles on them and wear out they increase the clearances which can cause a drop in engine oil pressure.
As long as you got at least a few lbs of oil pressure you should be good to go.
If your oil pressure drops to actually zero then you'll hear tapping noises in the valves which means you should shut the engine off.