When my online wells fargo account says I have $700 in available credit, what the hell does that mean?

Hey everyone, I know I'm probably gonna get a bunch of spam answers but trying never hurts. I know nothing of banks, I've never had an account until I was forced to by my University, unless I couldnt eat at the school cafeteria. So I gave in. I was looking at my online wells fargo account and it said I had $700 in "available credit", I asked my roomate what it was and he told me it was basically $700 that I can use on my card? Which I think is bullshit, cause I cant see a bank GIVING people $700 for FREE. What does this mean?