There is a frog. The frog has a small mouth. The frog has a problem. The poor frog can't eat with a small mouth. So the frog's friend has a solution. The frog's friend makes tiny sandwiches for the frog.
Nosotros somos de Guatemala.
Because ser is for more permanent things, like character traits or nationalities, while estar is more for temporary things like feelings or current location
How to remeber ser and estar easy
for how you feel or where you are, always use the verb estar