This is a holder for a handheld vacuum cleaner. It can be mounted to wall or to a garage shelf  (the one which can be purchased at OBI home supply store, but perhaps the dimensions fit other too).

I uploaded the FreeCad file too, it has a spreadsheet in it so the parameters can be changed for your vacuum. 

The default dimensions are for a Smania ProFlow vacuum cleaner (https://smania.store/en/product/cordless-handheld-vacuum-cleaner-proflow/) which can be seen in the photos.