ok so i took my car to the dealership to get fixed i have a 99 z24, and they said that my #3 rod bearing broke. i have no clue wut that is or does so anyone wanna fill me in i'd be very happy thanks.

A rod bearing is a small piece of metal that look like a slice of a soda can. The two halves make a full circle. Sort of a loop of flat metal. It goes in the piston rod where it connects to your crankshaft. Any auto parts store can show you one. Should cost very little. Ones for my 94 list for $2.99 plus $1.29 for plastigague. The labor will cost you plenty especially if they must turn your crank. If you were not racing and you shut the car off quickly you can probabily just replace the bearing insert(rod bearing) The plastigague will tell. I guess you ran out of oil? That is the usual cause. That knocking sound is horrible. Good Luck.