Think of it like this: they are words that are "phonetically identical" but "semantically distinct".
Here are some examples:
* To, too, two: These words sound the same but have different meanings and uses.
* There, their, they're: All sound the same but refer to different things (place, possession, contraction).
* See, sea: These words sound the same, but one refers to the act of seeing and the other to a large body of water.
Homophones can be confusing in writing, but they can also add a bit of spice to language and make it more interesting.