In Spanish, "ser" is a verb that means "to be." It is one of the two verbs used to express "to be" in Spanish, the other being "estar." "Ser" is used to describe essential characteristics, identity, origin, time, and more permanent states, such as:

• Identity: Yo soy estudiante. (I am a student.)
• Origin: Ella es de México. (She is from Mexico.)
• Time: Son las tres de la tarde. (It is three in the afternoon.)
• Characteristics: El cielo es azul. (The sky is blue.)

If you want, I can also provide the conjugation of the verb "ser."