Egalitarianism (sometimes called equalism) is the philosophy that all people deserve equal rights. Feminism is egalitarian, but some people who self-identity as "egalitarian" reject feminism, seeing it as either too focused on women or as a conspiracy to take away power from men and give it to women.
Feminists focus on women and non-binary people because they are disproportionately affected by gender inequality. Whilst there are obviously exceptions, men tend to be less vulnerable to issues such as rape, objectification, sexual harassment, denial of power, obligated parenting, strict beauty standards. These issues disproportionately harm women and non-binary people.
Feminists can, and often do, discuss and and work on issues that affect men. It’s just that women are frequently discussed because centering the experiences and needs of women is a more effective way to effect change than centering the experiences and needs of men.