The first ionization energy is the energy it takes to remove an electron from a neutral atom. The second ionization energy is the energy it takes to remove an electron from a 1+ ion. (That means that the atom has already lost one electron, you are now removing the second.) The third ionization energy is the energy it takes to remove an electron from a 2+ ion. (That means that the atom has already lost two electrons, you are now removing the third.)
And 2nd ionization energy is higher than 1st ionization energy, 3rd is higher than 2nd, and so forth.