The Senate confirms the presidential appointments of just about everything, specifically the Cabinet officers and other top federal officials such as the Supreme Court justices for example. The Senate must do this with a majority vote, this is in part a function of the system of checks and balances. The Senate must check the President in his appointments to keep this balance of power, just like the legislative branch can’t make laws without the president always, since he has powers such as veto, etc. Have a great day, I hope this help, and God bless!