how old was snow supposed to be in "the stable boy"?

i ask that cause in one scene regina asked her if she knew what a secret is. lol i would think a kid at any age would know what a secret is lol snow couldnt have been less then 9 maybe 10. dont mean to make fun of regina in any way. i just always thought it was funny and strange that she would ask snow if she knew what a secret was. lol