what does "on-call" mean?

LOL no you don't get paid the whole weekend. On call means anytime between those days and hours they can call you at anytime they need you to come in..As in if it is 3am and they need you, that is when you would go in.

On call means that you're not actually at work, but if they happen to need you they can call you and you have to come in. At any time.
At the hospital I work at, CNAs get paid something like $3.00 an hour just for being on-call, but of course if you have to come in, you get paid your full salary while you're there.
We used to actually get paid MORE than our normal salary if we got called in (because in addition to our regular hours we have to do a certain amount of on-call time), "on-call pay", just a little bonus for coming in at three in the morning or whatever. We don't anymore though, part of the cut-backs going on due to the economic recession.

Pretty much means your screwed!! Ok Ok not exactly but you carry the pager or the phone and basically wait for it to ring and that is usually the only time your friends want to go off and do something and you can't b/c your "on-call". I worked for Hospice and we were on call roughly once every two months we got paid $10.00 extra to carry the pager and then regular pay while we were "out" unless you had already wk'd 40 hrs and that was the only thing good if it ran into overtime!!