What's this hole with a lock symbol on the back of my monitor?

Using the Security Slot security lock slot Our universal security slot has a standard T-shaped hook system, it secures any device that does not have a security slot Slim security cable lock security slot The Noble Locks Wedge slot is designed to solve the height issue of sleeker low-profile laptops Our patented design gives the lock head additional area to

security cable slot Buy a Kensington Slim N17 Combination Laptop Lock for Wedge-Shaped Slot