The following three simple words are used to express quantities in Portuguese:
muito many, much, a lot
pouco few, a little
algum some, a few
When describing items you can count (which usually end in “-s” in English as well as Portuguese), muito, pouco and algum all change according to gender and quantity:
Eu tenho muitos amigos. I have many friends.
Poucas pessoas sabem o segredo. Few people know the secret.
Eles compraram algumas prendas. They bought some gifts.
With uncountable nouns (such as virtues, qualities, or time, which usually don’t end is “-s” in either language), muito, pouco and algum stay in their singular form, while maintaining gender agreement:
A família não tem muito dinheiro, mas tem muita coragem. The family doesn't have much money, but has a lot of courage.
Ele tem pouca paciência para festas. He has little patience for parties.
Tens algum tempo livre? Do you have some free time?
Additional Expressions of Quantity
To emphasize how small a quantity is, you can actually combine muito and pouco into a single expression: muito pouco very little, very few. The same rules of gender/quantity agreement apply here, but only to the last word of the expression, pouco:
Há muito poucas casas aqui. There are very few houses here.
Falo muito pouco francês. I speak very little French.
Note that um pouco a little bit can also be used as a noun:
Só quero um pouco. I just want a little bit.
Já sei um pouco de português! I already know a little bit of Portuguese!