you're my 24

Used in EXOs song "twenty-four" as a repetitive chorus saying "you're my twenty-four, you're my twenty-four"

They are referring to the 24 hours in day. It really means "I love you all 24hrs in a day" or "I love you everyday".

Chanyeol says at one point "My day is yours" and Sehun says "As if my day and night were stolen" Basically theyre all talking about how much they love their partner no matter the time, place or situation.

P1: you know i love u right
P2: Yeah you're my 24
P1: oh my god