It’s a female threaded fastener that typically mates with a bolted solution. Screws go in a tapped hole; bolts go in a nut.

Metric, US Standard, and Locking Nuts

Acorn, Allen, Castle, Coupling, Die, Finished, Flange, Hex, Heavy hex, Heavy, Lock, Nylon insert, Square, Slotted, Structural, T-nuts, Wing

Every industry in the world uses nuts and bolts.

This is a double-sided joint so you need access to the backside including enough room for your torque tool to fit.

Find more information on Nuts here