-(으)ㄹ turns a verb/adjective into a noun-modifier that refers to something expected, intended, or likely in the future (prospective meaning).

With action verbs:

• 먹을 음식 (food to eat / that will be eaten)
• 만날 사람 (a person I will meet)

With adjectives (descriptive verbs): often means “will be / likely to be”, or a prospective state.

• 좋을 것 같다 (seems like it will be good)
• 어려울 수 있다 (may be difficult)

Note: with adjectives, -(으)ㄹ rarely modifies a bare noun directly; it mostly appears inside patterns like -(으)ㄹ 것 같다, -(으)ㄹ 수 있다, -(으)ㄹ 텐데.

Form:

• after consonant (받침): -을
• after vowel: -ㄹ