Several meanings can be given to the word vocation.

A universal meaning: All baptized persons are called to holiness.

A professional meaning: A state of life.

A personal meaning: Each person has a vocation, a mission.

The word vocation has a sense of call. Certain persons are called to a particular vocation.
We believe as Christians that God calls each man and woman to one of the states in life : to marriage, single life or consecrated life.