Howdy Aleksandar, I once owned a JCB backhoe a little older than that one. I loved it. It was a beast and worked hard all day.
The pictures look like that tractor is in pretty good shape.
Be sure to look at all of the hydraulic hoses. Look for cracks and leaks . A hose that breaks while working will spray fluid all over and cause a mess.
When you go to look at the tractor, before you start or move it, look underneath it, on the ground, look for oil or fluid spots that will show you where any leaks have happened while the machine was parked.
Look at all of the "rams", look for fluid leaks where the rams come and go in and out of the cylinders. if they are leaking they will need to be repacked. Also look at the rams to be sure they are smooth and shiney. If they are scratched they will eventually leak.
Start the tractor and lift the front
bucket off the ground, put down the outriggers and lift the backhoe up off the ground. Wait a few minutes and watch to be sure they stay up. Drive the tractor around, shifting through the gears. Just generally go through all of the controls etc.
Find out if you can get the operators manuals and the maintenance manuals. They may be expensive but they are worth having. You can find them
online if they dont have them with the tractor.
There are several online tractor forums that I found very helpful when I was just getting to know my machine.
Find out where you can buy hoses, fluids, and parts in your area. If you own one of these it is best if you have some mechanical skills. Or have a friend who will teach you.
I have owned three backhoes in my life and used them all the time . I think if you are going to be doing a lot of dirt work they are well worth it. If you get really good at running one, you can hire yourself out to others too!
Always be safe! Don't let anyone get close to you while you are operating the tractor. Never get under any raised hydraulic arm. They can fail and crush you.