The electronic configuration 1s² 2s² 2p⁶ 3s¹ 3p³ 3d² represents

since total no. of electrons here are 16 and original configuration(ground state) should be 1s² 2s² 2p⁶ 3s² 3p⁴ 3d⁰. 

So 1 electron each from 3s and 3p go into 3d in 2nd excited state.