This grammar form indicates that something is possible.

• 갈 수 있어요 [somebody] can go.
• 할 수 있어요 [somebody] can do it.
• 갈 수 있으면 갈께요 If possible, [somebody] will go.

To indicate that something is impossible, simply use 없다 instead of 있다.

• 시간 없어서 파티에 갈 수 없어요 [somebody] doesn't have time, so can't go to the party.