In English grammar, the object of a preposition is a noun, noun phrase or pronoun that follows a preposition and completes its meaning. The object of a preposition is in the objective case.
A word group made up of a preposition, its object, and any of the object's modifiers is called a prepositional phrase.
In contemporary language studies, the object of a preposition is sometimes described as a prepositional complement.
Examples:
1. She was writing on the wall.
Preposition: On
Object : the wall
2. They walk the path to the church.
Preposition: to
Object: the church