Screw is a new move property introduced in Tekken 7 to replace bounds, the Japanese have dubbed this きりもみ kirimomi which means aerial tailspin; a screw move will force an airborne opponent to spin around 360° and land with their legs pointing vertically whilst their backs/heads touch the floor.
In this state, players are vulnerable to combos and continuations of combos, and as such, low parries can now grant full combos with use of moves with a screw property.
Like Bounds, Screw moves can only be used once in a combo, however unlike bounds, screw moves can be used after a bound; i.e. wall/floor/balcony break bound -> screw. Note that a combo that uses a screw move and then gets a floor/balcony/wall break bound, cannot use another screw move as the property is only used once per juggle/combo.