Bruises (feat. Ashley Monroe) Lyrics

Lyric discussion by ireeen 

Cover art for Bruises (feat. Ashley Monroe) lyrics by Train

"One that's five and one that's three"

What does that mean? I've been wanting to find out every time I hear it on the radio!

English is not my native language so I might be missing something very obvious I guess?

Song Meaning

She has two kids. One is five years old and the other is three years old.