These brakes are single-pivot side-pull caliper brakes. They can work well, but only if they are well made - I personally never had much luck with Weinmann brakes.
For the rear brake, pretty much the only thing you can try is replacing the brake pads. The front ones don't look very worn, but the rubber gets hard with age and loses its effectiveness.
The front brake looks broken beyond repair. The part I circeled red should be attached to the green part, but the connecting part seems to have broken off.
You might be able to find a replacement, but I would recommend replacing the whole brake for a better one.
I am pretty sure this is a side caliper brake. The front one broke 1-2 days ago while I was in the supermarket, see Pic.
Is this someone tampering with it or just broke because oigf material stress/oldness?
Anyways, I don't feel safe with only one brake, and truth be told, if it rains I don't feel safe with both because they do not pull enough especially if there is other traffic.
I consider myself decently knowledgeable and have most tools, I have done a lot harder repairs, but up unhtil now I've only ever had V-brakes so I am out of my depth with this, and especially with brakes I do not want to just try stuff.
Where can I learn how to adjust and make the back one have more pull, and to fix the front one?
Here's another pic