Concrete floor grinder (also called a diamond concrete grinder).
The four red rotating discs are fitted with diamond grinding cups/segments. They are used to:
Remove old paint, epoxy, glue, and coatings from concrete floors.
Smooth and level uneven concrete.
Prepare concrete before polishing or applying new coatings.
Remove surface imperfections.
The black brush around the edge helps contain dust and is usually connected to a vacuum for dust collection.
This type of grinder is commonly used in construction, flooring, and renovation work.
If you're interested, I can also estimate its price based on the brand and motor size.