Cyclohexanone is treated with (i) $\mathrm{CH}{}_3\mathrm{NH}{}_2$, mild acid (pH about 5-6); (ii) $\mathrm{NaBH}{}_3\mathrm{CN}$. The product is

The ketone and the primary amine give an imine, which is protonated to an iminium ion. $\mathrm{NaBH}{}_3\mathrm{CN}$ is a mild hydride donor that reduces the iminium ion faster than the ketone, giving the secondary amine, N-methylcyclohexanamine (reductive amination).