Using density functional theory we investigate the lattice instability and electronic structure of recently discovered ferroelectric metal LiOsO3. We show that the ferroelectric-like lattice instability is related to the Li-O distortion modes while the Os-O displacements change the d-p hybridization as in common ferroelectric insulators. Within the manifold of the d orbitals, a dual behavior emerges. In the ferroelectric transition the empty e(g) orbitals change their hybridization with the oxygen p orbitals, while the t(2g) orbitals are responsible for the metallic response. Interestingly, these orbitals are nominally half filled by three electrons, a configuration which suffers from strong correlation effects even for moderate values of the screened Coulomb interaction.