there are two important thing in endgame, checkmate and promotion
About studying end games
How do you study best? Everyone is different.
For me (maybe not you) I like to study
complete games w. interesting endings,
thin books that I can actually finish, and
endings in a thick book that are similar to one in my last game that went that far.
Some people can take a thick book, start on p.1 and work thru to the end. (Not me. ) So (my suggestion) pick a plan that fits what you will actually do.
- Bill

There is a book writted by Jesus de la Villa, "100 Endgames You Must Know" that is an excellent material to understand endgames.
And another one by Dragan Barlov that is very good too, but Im afraid I only know the spanish edition, "Disculpen las aperturas... los finales son fundamentales"
Those are very interesting to learn endgames
As I played chess I found out that I was very weak in the end game. So I decided to study about end games. But I don't know how. Any tips?