Just before Meiosis a cross over event may occur. wut is this process and wut is the result?

It is not just before meiosis, it is during meiosis the crossover event occurs. The process takes place during Prophase I. The chromosomes get divided longitudinally but still attached to centromere. The pairing of the chromosomes takes place. The sister chromatids get crossed over and the part of the chromosomes get exchanged. This is called as crossover event.