I was trying to understand the difference between being a orientable vector bundle and orientable manifold.
Taking a embedded non orientable surface $S$ is orientable 3-manifold $M$,as embedded submanifold $S$ has tubular neiborhood diffeomorphic to the normal bundle of $S$.therefore as open subset of orientable 3-manifold $M$, the normal bundle $NS$ is orientable manifold.
However I was confused why $NS$ is not a orientable vector bundle, moreover is the unique non orientable vector bundle on $S$ of rank 1.