Phrasal verbs consists of a basic verb + another word or words. The two or three words that make up a phrasal verb form a short 'phrase' - which is why we call them 'phrasal verbs'.
Phrasal Verb:
light something up
Meaning / Example:
1. to light a fire, a gas burner, etc. > I lit the kindling up and soon the fire was going.
2. to light something to smoke, such as a cigarette, pipe, etc. > She lit the cigarette up and took in a great breath of the smoke.