abcs
nounUK /ˌeɪ biː ˈsiːz/
US /ˌeɪ biː ˈsiːz/
The ABCs are the letters of the alphabet that you learn first.
My little sister is learning her ABCs at school.
OTHER MEANINGS
2. The basic facts or first steps of a subject.
The teacher taught us the ABCs of math before giving us harder problems.
3. A children's book or song that teaches the alphabet.
Grandma read me an ABCs book before bedtime.
4. The simplest and most important parts of something.
Learning to share is one of the ABCs of friendship.