It's basically contractions that don't open or soften your cervix, so your whole belly will just tighten and feel hard for a few seconds or longer

They can be a sign of dehydration, so chug some water and change your position and within a couple seconds your stomach should loosen up again.

For me my stomach gets rock hard, tight and I have some discomfort like cramps but nothing that isn't bearable, I've been having them since 17 weeks which is normal for me.

Are they like shooting pains or something?

Just feels uncomfortable for a little bit they usually don't hurt

They're really not that bad, if you walk around and breathe they go away.

Idk I've never had menstrual cramps either