Ser and Estar are both used to mean "to be" in English. We will focus on SER for now.
Ser means to be in English. We use ser to identify people, say where they are from, and more long term characteristics/traits about people and objects. Ser is used for more existential things, like to be tall, thin, a boy, girl, black, white, a teacher, a student, etc.
Here is how ser is conjugated in the present tense:
Yo soy = I am Nosotros(as) somos = we are
Tú eres = you are Vosotros sois = You all are (only used in Spain)
Usted es = you are (formal) Ellos(as) son = they are, they are (all female)
Él es = He is Ustedes son = you all are (used in Latin America; used in Spain for formal occasions)
Ella es = She is
Example sentences:
Yo soy Pedro = I am Pedro Nosotros somos estudiantes = We are students.
Tú eres una chica = You are a girl. Vosotros sois inteligentes = You all are intelligent (Spain)
Él es un maestro = He is a teacher. Ustedes son ricos = You all are rich
Ella es mi amiga = She is my friend. Ellos(as) son extraños = They are weird.
Usted es muy alto = You are very tall (formal)
