Molto e poco can either be adjectives or adverbs.
If they are adjectives they qualify or modify a noun, if they are adverbs they modify a verb, an adjective or another adverb.
A common mistake is to leave molto e poco unchanged, when they should be agreeing in gender and number with the subject of the sentence:
- Sandro ha molti soldi (here molto is an adjective, it has to agree with "soldi")
Sandro has lots of money
- Marco mi ama molto (here molto is an adverb, no need for agreement)
Marco loves me a lot
- Abbiamo solo pochi minuti (pochi here is an adjective, it has to agree with "minuti")
We only have a few minutes
- Fra poco comincia lo spettacolo (poco here is an adverb, no need to change it)