Mitosis is the replication of exact copies of cells. most cells in your body undergo this process in order to duplicate. These cells go through interphase, prophase, metaphase, anaphase, and telophase before completely splitting.
However meiosis only occurs in sex cells (sperm/egg). These cells (technically) divide twice, thats why they have interphase, prophase, etc. then they have Interphase 2, prophase 2, etc.
This extra split in chromosomes allows for the sperm and egg to combine with the right ammount of genes later on.