A more thorough explanation:

Definition: A vicar is someone who performs the duties of another person, usually as a substitute. In the context of religion, a vicar is also the person who holds an ecclesiastical benefice.

For example, if a teacher is absent from school, a substitute teacher may be hired to act as a vicar and perform the duties of the absent teacher. In the church, a vicar may be appointed to serve as a representative of a higher-ranking member of the clergy, such as a bishop.

Another example of a vicar is a priest who is appointed to serve a parish in the absence of a rector. The vicar would perform the same duties as the rector, such as leading worship services and providing pastoral care to the congregation.

These examples illustrate how a vicar is someone who takes on the responsibilities of another person, either temporarily or permanently, and performs their duties in their absence.