A preposition is a word that expresses relationships between people, places, and things. They help us to understand a time, way or position connection between two or more things. using them in your writing helps your reader to imagine your setting and how things move within that setting more effectively.
Her bag was under the desk. The cat slept on the pillow.
They arrived 10 minutes after the speech started. Class begins at 9 am.
Directional prepositions(the way something is done):
they watched each other without speaking. The popcorn sat between them on the couch.
More than one word… Sometimes prepositions are phrases, not just single words.
We sat next to each other. The hotel is perched on top of the cliff.