Every bike and tire will have a different pressure, which relates to the weight they carry, the design of the wheel tread and thickness and your own, personal preference. Typical pressures range from 22PSI to 35PSI, with more air generally being held in the rear tire as this is where most of the weight tends to be gathered.
If you spend most of your time on the forest floor or on the road, you’ll likely want a slightly higher PSI, since this will improve your speed and help you move forward with less effort on your part. If you’re looking to go uphill, a slightly lower pressure will ensure that you will have an easier time, since the lower the pressure, the higher the contact between the surfaces of your tire and the floor.
Generally speaking, a tire pressure under 20PSI will be much too low and could cause damage to your wheel rims and create pinch punctures. Meanwhile, a PSI that’s too high will create less grip and therefore create an unstable bike. If you still aren’t sure about the best range for your bike, you should be able to see the recommended PSI either on the sidewall of the tire, or in the manufacturer’s handbook.