What don’t you understand about all the responses you’ve gotten thus far? FAFSA is a federal application that you fill out. If you meet the criteria - ie, low income - you may qualify for a Pell grant. This is a small amount, comparitively, and will not cover or “pay the fee” for your degree by any means. As it’s federal, this is only for citizens/perm residents. You can also get a federal loan, but this doesn’t seem to be what you’re asking.
“Financial aid” is a very vague term, and differs by school and individual situation, which is why there is no yes or no answer to your questions. Some students will not get any aid and some will get much aid. It depends on the situation. Are you an international student? It doesn’t seem like you’re familiar with American higher education.