Prepositions are words that show the relationship between a noun or pronoun (the object of the preposition) and another word in the sentence. This relationship can be about:
* Location: on, in, under, above, behind, beside, etc.
* Time: before, after, during, since, until, etc.
* Direction: to, from, towards, into, out of, etc.
* Other relationships: with, without, according to, because of, etc.
For example:
* "The book is on the table." ("On" shows the location of the book in relation to the table)
* "We went to the store after dinner." ("To" shows direction, "after" shows the time in relation to dinner)
* "She wrote the letter with a pen." ("With" shows the tool used in relation to the action of writing)