The R6 frame size is a mechanical envelope common across the ACS510 line in this current range. It determines the mounting footprint, the gland-plate layout, and the bus-bar or cable entry spacing inside the panel. If your existing cabinet was laid out for an R6 drive, this one slots in without re-drilling the backplate or re-routing the main power cables.
The WEEE category is Product Not in WEEE Scope, which means this drive falls outside the European Waste Electrical and Electronic Equipment directive's scope — typically because it is classified as industrial, large-scale fixed installation equipment. No WEEE registration or take-back obligation for the buyer in most EU jurisdictions, though local implementation varies.