Body and soul, yes.
so then when kiari lost here heart why did her body stay? shouldnt it have become namine?
Nope, because Kairi is a PoH. She as far as we know, her Body - due to her Heart not having became a Heartless - was never cast off into the Darkness and thus never became a Nobody (until Xion'll possibly rebunk this).
could this mean namine isnt kiaris direct nobody?
She's much more Sora's Nobody than Kairi's in that aspect, seeing how even Nomura confirmed her existence was made possible by Sora.
and also you need a storng heart right? kiaris heart isnt strong! there must be a mixtake!!!
1) <3
2) see, that's the thing though, Kairi's
Body and Soul didn't become a Nobody. Sora's did - it became Roxas. Kairi's Heart leaving that same Body+Soul on its way to becoming a Nobody made for a by-product based on Kairi's Sense of Self - being Namine. Another reason why Namine is all but nothing, possibly - because the Heart she was based on wasn't truly strong enough to sustain a Nobody (though they could always shrug it off with Kairi's Pure-Heartness making up for it).