There is no male-only chess, women can also compete. Female-only chess clubs and tournaments are a way to encourage women to get into chess in a less hostile, more welcoming environment. Ultimately it's an attempt to bring more diversity to the male-dominated game. In 2019 for example, women made up a higher percentage of chess players then ever before, but still only accounted for 14.6% [0] of registered players.

[0] https://www.chess.com/news/view/team-battles-femme-batale-no...