Definition of "Less" :

adjective: (comparative of little' usually used with mass nouns) a quantifier meaning not as great in amount or degree

"Of less importance."

adjective: (nonstandard in some uses but often idiomatic with measure phrases) fewer

"Less than three weeks."

adjective: (usually preceded by no') lower in quality

"No less than perfect."

adverb: used to form the comparative of some adjectives and adverbs

"Less interesting."

adverb: comparative of little

"She walks less than she should."