Spermatogenesis and oogenesis are the processes by which sperm and eggs are obtained, respectively.
In both cases, a diploid cell (spermatogonia or oogonia) gives rise to haploid sex cells through a process of meiosis.
However, men produce many more sex cells than women and produce them constantly, while women already have a certain number of eggs that they will release throughout their lives.
In the case of females, during embryonic development, they generate a certain number of primary oocytes (from oogonium). These primary oocytes remain stagnant in prophase I of meiosis within the female until puberty arrives. When a woman reaches puberty, hormonal changes drive meiosis, causing a primary oocyte to mature each month into an egg that can be fertilized by a sperm.
Something that is important to note is that during meiosis in female sex cells, 4 eggs are not obtained for each oogonium because along the process 3 "polar bodies" are released and degenerate, this is an explanation of why men generate more sex cells because male cells carry out meiosis normally and also occurs constantly, not every month.