The psi range on the side of the tires is good to bracket your tire pressure (pressure is what you are setting, psi is the units*). You should know that the thinking has changed over the years on tire pressure. This article gives some guidelines:
https://www.cyclingweekly.com/news/p...ressure-270668
One thing to keep in mind: the optimal tire pressure depends on tire size. If your tires are 32mm wide, you can use a lower pressure than if they're 25mm. As a guideline, I just bought new tires for my wife's bike. You go by rider weight plus bike weight. For about 170lbs, I inflated new 32 mm tires (Bontrager R3) to 55psi in front, 65 in the rear. She loved it - much better than the 70-80 psi we had used before. But the article cited is for road bikes: search around for similar articles suited to the type of riding you intend to do.

The tire guidelines should get you to a safe pressure that is within 10psi or so of the pressure that will have you most comfortable and confident. I would especially emphasize that whatever recommendations you find for tire pressure, DO NOT exceed the max pressure recommendations on the tire.

*psi is pounds per square inch*, which is a pressure, not a weight. The "bar" is the pressure unit used elsewhere in the world. It's about 14.5psi. Atmospheric absolute pressure is about 14.7psi. So one bar is about one atmosphere. There's a discussion on gauge pressure vs absolute pressure (your gauge reads the difference between the tire and the atmosphere - the absolute pressure is the gauge pressure plus atmospheric). But that's not necessary: just remember that when properly inflated, the pressure your tire gauge indicates should be within the range specified on the tire. And all the tire pressure recommendations are for gauge pressure.