Four jobs in one character. As a modal verb:
可以 (can / may),
可 + verb meaning -able as in
可怕 (scary) and
可爱 (cute). As a conjunction:
可是 (but). As an emphasis adverb before adjectives:
可 + adj +
了 means "really very ___" —
可好吃了 (really tasty). As a verb:
认可 (to approve / endorse).