Affordances are the actions an object makes available. A pen can be used for writing, for drumming, for stabbing, for prying, etc. It’s a technical term used in psychology and applied psychology fields (interaction design, industrial design, etc.)
The lowly HTTP URL (web address) has two important affordances, retrieval of information with a browser and as a source of universal uniqueness; no two web addresses are the same.
“Psychologist James J. Gibson originally introduced the term in his 1977 article “The Theory of Affordances” and explored it more fully in his book The Ecological Approach to Visual Perception in 1979.”