Some T-cells become memory T-cells, some go to the battlefield, and some activate B-cells. The B-cells divide rapidly and produce strong weapons, antibodies. They often die from exhaustion.
The helper T-cells stimulate B-cells, macrophages, and neutrophils and tell them not to die. They also tell plasma cells which type of antibodies are needed in the fight.
Billions of antibodies flood the battlefield and disable many bacteria. Macrophages eat them. Once the infection is wiped out, body cells are replenished and most immune cells die (with the exception of memory cells)