Is a verb an LY word?

No. The ending LY is characteristic of adverbs, Words that modify verbs (and adjectives and other adverbs). Examples are calmly, easily, simply, quickly, and generally.

But not all Words ending in LY are adverbs.

Nouns: belly, doily, folly, gully, reply

Adjectives: hilly, holy, jolly, silly, surly, ugly

Verbs : fly, imply, rely, supply