So, we have a comforter and we have a light blanket.
Usually, there is a top sheet, "sheet," that you put over you in between your body and the blankets, and this top sheet is sometimes called a flat sheet.
The sheet that goes on the bed itself--that goes onto the corners of the bed--that's called a fitted sheet, a fitted, "fitted," sheet.
So, we have a fitted sheet on the bed that you sleep on top of, then we have a top sheet and then a blanket, sometimes, if it's very cold, a comforter as well.
I say in the story that "I sleep with two pillows." A pillow, "pillow," is what you put your head on when you sleep.
Now, "for some reason," I say I "have different colored pillowcases." This is true, actually; I have a black pillowcase and a blue pillowcase for my two pillows.
I think the reason is I am too lazy to go and buy a new pillowcase.
Well, the pillowcase, "pillowcase," (one word) is the thing that you put over the pillow so the pillow doesn't get dirty; we call that the pillowcase. I say, "Well, at least the sheets match." We already know what a sheet is.
When we say the sheets match, "match," we mean that they are the same color or two colors that look good together.
We use that verb, to match, when we are talking about clothing as well, or anything where you have two colors.