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.