I'm pretty sure LO understands what NO means when I say it but when she says it I have no idea.

Sometimes she means NO, other times she'll she sees the dogs coming over to her when she's snacking says No to them but them throws them a treat. Other times she'll say No when I ask her to put her socks on or something but then she'll smile and hold out her foot.

I'm starting to think she just likes saying it because it's easy to say (she doesn't say many words yet).