The sad thing is I agreed only because I need money since I'm still an undergraduate and I wanted to lift some of the weight off my mothers shoulders (she's a single parent).

Not sad, most people take jobs on this basis.

But I don't like my job and there are reasons: in the last two months I haven't learned a simple new thing that will help me be better with my tasks

Are you sure? I would suggest taking it upon yourself to learn new things in this role, even if it might slow down your progress. Try writing your code in different ways than the immediately obvious ones.

the company has something like a framework and I'm afraid that if I spend years on it I won't be able to find a job after that, because I won't be qualified enough

You're an undergrad working on programming. The number one benefit you're getting from this job for your post-graduate life (money aside), is that you have a full time job during school, which will give you a huge advantage over candidates who did not. That it's also presumably related to your field is a non-factor.

We have devs working at my current company that had to program in COBOL during undergrad. It's not a factor.

the salary is small for the industry

For the industry, or for someone in the industry with your education and experience? If it's the latter, ask for more money.

I dread going to work, and can't wait for the work day to end.

You have, it sounds like, a couple months until your contract is up - use the time to try to find something better. But be honest with yourself about the other positions, and whether they really solve the issues you've outlined here. End of the day, only you can weigh this job vs. another job vs. the loss of salary.