Question

In my textbook (page 336 for those of you that own it), itsaysthere is H 1s¹ and He⁺ 1s¹.It saysit takes 1312 kJ/mol of energy to remove the 1s electronfromhydrogen, but 5251 kJ/mol of energy to remove itfromHe⁺. It also says, although eachelectron is in a 1sorbital, the electron in the helium ion isattracted to the nucleuswith a 2+ charge, while the electron inthe hydrogen atom isattracted to the nucleus by only a 1+charge. Therefore, theelectron in the helium ion isheld more tightly, making it moredifficult to remove and makingthe helium ion smaller than thehydrogen ion.

I don't understand the part highlighted in red. Cananyoneexplain please?