How can you tell for sure what a kitty is hiding?

[Thorn Witrial]

Hi folks.

I've seen many people talk about kitties hiding traits, and seen kitties for sale that say they are hiding such and such trait. I've also poured over the google breeding chart docs. I am having a hard time wrapping my head around this.

Can anyone explain it more simply? I'm tired of feeling thick. ^_^;;

Thanks.