Quantitative adverbs like demasiado (too), bastante (quite), un poco (a bit/a little) and muy (very) express intensity. They can modify adjectives and other adverbs.
Adverbs are invariable: they don't need to agree in gender or number with the words they are modifying.
Have a look and listen to the following examples:
Un poco (a bit/a little)
Notice how the adverbs are invariable: their form does not change when modifying masculine, feminine, singular or plural words.