use of lcd

hello
can any one help me to understand these code

lcd.begin(16, 2);
PCICR |= (1 << PCIE2);
PCMSK2 |= (1 << PCINT18) | (1 << PCINT19);
sei();
what pcicr ,pcie2 ,pcmsk,and pcint mean

They have nothing to do with the lcd instance. They are register names that are documented in the Atmel documentation for your board.

The context where that snippet came from would be useful.