This expression introduces something that your reader or listener already knows, but you want to remind them of.

"As you're aware," is a formal phrase. A more casual version is "As you know,":

As you know, you're supposed to go through me for any help you need with tech issues.

You can add "well" to talk about something that your audience knows well already:

As you're well aware, we don't allow smoking in the building.

You can use this phrase when you're annoyed by someone who keeps making the same mistakes, or just to be helpful.