Steam is usually very secretive about their sales dates but this time they leaked the date via a Youtube video.
The video was posted by Steam a while ago and it is still up at the time of writing but the video is unlisted, so you can’t search for it on Youtube. There will be plenty of AAA games on discount such as Red Dead Redemption 2, God of War, Monster Hunter Rise, Dying Light 2, and many more. Of course, it is not just AAA that are on sale, there are plenty of indie titles too.
As with all other Steam sales, you can expect to craft trading cards and badges to customize your profile. They also mentioned ‘mystery badges’ but didn’t go into details about them. Guess you just have to wait and find out when the sales start.