It's a descriptive name for a player who prevents the other team from scoring close to the basket. There are statistics that monitor how good a player is at this, it's a real thing in the same way the the term "3 point shooter" is a real thing.
WCS in the draft!
I agree,
The standard PG,SG,SF,PF and C or 1,2,3,4,5 are only a very basic description of basketball positions. At any level but particularly the NBA other positions / roles have developed.
To list a few
Stretch 4
3+D wing
Rim protector
Combo Guard
face up 4
"rim protector" is currently a hot term because the Cs lack a great one.