ABC's

US: /ˈeɪˌbiˈsiz/ ,(ā′bē′sēz′)

WordReference Random House Learner's Dictionary of American English © 2025

ABC's or ABCs/ˈeɪˌbiˈsiz/   n. pl. 

1. the alphabet:
   Children learn their ABC's in kindergarten.
2. Education the basic skills of any subject.

WordReference Random House Unabridged Dictionary of American English © 2025

ABC's  (ā′bē′sēz′), n. (used with a pl. v.)

1. Also, ABC. the alphabet.
2. Education the basic skills of spelling, reading, and writing:
   learning the ABC's in the early grades of school.
3. Also, ABC. the basic or elementary facts, principles, etc., of a subject:
   the ABC's of electricity.

Also, ABCs