Using INTERRUPTS in 89v51rd2

I am given a piece of code from my college professor to debug it. I have a small doubt in some portion of the code which is written below. Can anyone please explain me the code. and also tell me at what situation INTERRUPT is raised.

void initialize_timer2()
{ RCAP2L=0xcb;//0xe5; RCAP2H=0x7d;//0xbe; T2CON=4; ET2=1; EA=1;
}

Please help me

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