What does it mean to accept or decline college admissions?

I got a letter from a university saying that I got admitted into the college. They told me to log onto my account and make sure to accept or decline my admission.
If i accept it does it mean that I’ve confirmed that I will go to that school, like I can’t accept any other college admittance? Or if I accept it will I be guaranteed the spot in the college, but not actually confirm my decision of going there?

So you have received an admission from either an early action school or a rolling school, correct? Because if it was an ED school you would have to attend.

If you applied EA to your top choice, you can accept the offer of admission. Then you would not apply to any other schools and you will attend there.
However, if you still intend on applying to other schools, you should not accept the offer of admission yet.

Unless this was an ED acceptance, you don’t have to make a decision until spring. There are just telling you how to tell them once you do make a decision. They are not telling you that you must do it now.

You can accept admissions and change your mind at any time up to May 1st and choose a different school, usually. This of course doesn’t apply if you applied ED, and you may lose your deposit (i.e. No refund). You cannot have deposits at two schools at once however, so if you later decide to deposit somewhere else, you’ll have to withdraw your commitment to the first school.