Simplify the following text for a Grade 6 native English-speaking person.
Original: A phrasal verb is a combination of a verb and a preposition , a verb and an adverb , or a verb with both an adverb and a preposition , any of which are part of the syntax of the sentence , and so are a complete semantic unit .
Simplified: Phrasal verb is the name given to an English verb which is composed of two or three words . One verb is combined with a preposition ( like on , in , under ) or an adverb ( like up , down , away ) .