El verbo SER

Yo soy : I am

Tú eres : you are (informal)

Él es : he is

Ella es : she is

Usted es : you are (formal)

Nosotros/nosotras somos : we are

Ellos son : they are (masculine or mixed)

Ellas son : they are (feminine)

Ustedes son : you all are (formal)

Tú is used with family, friends, classmates, people you know well,

Usted is used with older people, your teachers, people you may not know to show respect and courtesy,

used to identify people or things

used to refer to a person without mentioning the person's name

he = él, she = ella

¿Usted es profesor? : Are you a professor?

Sí, soy profesor de historia : Yes, I am a history professor.

ellos and nosotros can refer to groups of people that consist of males only or of males and females

ellas and nosotras can refer to only two or more females