Maps are derived from an analogy of the plain English visual (physical or digital) map, a data structure (tool) to get from here (key) to there (value). Maps contain keys which indicate or provide values.
For example your current address and your destination address (a cumulative key) return an optimal route (a kind of value);
https://docs.oracle.com/javase/8/docs/api/java/util/Map.html
https://en.wikipedia.org/wiki/Map_(higher-order_function)
https://docs.oracle.com/javase/8/docs/api/java/util/TreeMap.html