Question

When do I use uno una unos unas in spanish and when do i not?

Answer 1

One person male= Uno
One person female= una
Group of males= unos
Group of females= unas
but you also have to take in mind the amount of people and they’re gender. If there is 6 men the group is considered “unos” if there are 6 women they are considered “unas” but if on man comes into the group and now there are 5 women and one man they become “unos”
One man is all you need for the whole group of people to be considered male so that how you should address them
Example:
Tengo unas amigas= i have some friends (all females)
Tengo unos amigos= i have sample friends (all males) (same if they’re are any females involved as long as there is atletas y one male in the group your talking about)
Tengo un amigo= i have one friend (male)
Tengo una amiga= i have one friend (female)

Answer 2

When you're talking about nonspecific things.
it's like (a) and (an) in english.
uno is for singular masculine.
una is for singular feminine.
unos is for plural masculine.
unas is for plural feminine.