-(으)ㄹ 수 있다

In Korean, "can [v.]" is expressed with a phrase equivalent to "there is a way to [v.]."

[v. stem] + -(으)ㄹ 수 있다

to be able to [v.]

[v. stem] + -(으)ㄹ 수 없다

to be unable to [v.]

The word 수 has many meanings, but here it is used as to mean "way," as in "there is a way to [v.]."

References