For the basic precise positions, that need to be known by heart:
over the years many of my students have learned the basics very quickly and easily from this little gem of a book, already mentioned in the thread:
https://www.amazon.com/End-Games-Chess-Theo-Schuster/dp/0718823265That's an easy read that will give you a head start down a path that never ends. (The James Howell book is also very good, but bigger and harder to digest.)
Later, for more general endgame strategy, judgement and technique:
How to play the endgame in chess, by Barden, again as mentioned earlier - great if you can find a copy and don't mind descriptive notation. Otherwise, Endgame Strategy by Shereshevsky or How to Play Chess Endings by Mueller & Payeken - great, but maybe not such an easy read as Barden.
But as a player gets stronger and plays more endings it's also useful to have a more thorough book of precise positions and examples of all types of endings, primarily for reference. One of the best ways to learn how to play a particular ending is after it has arisen in one of your games, when it's best to analyse it yourself first, then with an engine, then look up that type of ending in a good reference book, such as Fundamental Chess Endings or Dvoretsky's Manual.
The above constitutes an itinerary; but none of us ever reach the destination of true endgame mastery!
PS Someone wrote something like: "The best endgame book is... the one you actually read! Most players have several such books gathering dust on their shelves."