To tell the truth, it's a complex question, like "why are there no female Christian priests". Christianity is a wide thing, with lots of subdivisions. So is freemasonry.

Why no woman ? There are historical reasons: a founding text (Anderson's Constitution) states that to be a Freemason, you have to be a free man. There are also old initiation rituals (a bit like a Masonic baptism) where the person is bare-chested. For traditionalists, this forever excludes women. This is particularly the case in the Anglo-Saxon world. Traditinnalists also often exclude atheists, LGBTQIA+ people, etc.

But worldwide, there are also progressive lodges, mixed or even feminine (which accept male visitors, but do not initiate men). I live in Europe, and in my loge we are about 10 men and 20 women. Lots of us are social workers, teachers, nurses or public servants. Lots of us are atheists or agnostics. Some of us are gay, lesbian or bi.

About what we do, one more time: it depends. The main idea is to have philosophical questionings, based on ritual and symbolism (A bit like a religious person who uses a holy text to nourish their philosophical reflections). All lodges also have charities, because the aim of Freemasonry is to improve oneself in the hope of making the world a better place.

But some progressive lodges (like mine) go further and are places for reflection on society, in a place where everyone can share their point of view without being cut off (this is an absolute rule) and without judgment.

In these lodges, all kinds of issues of social progress are discussed, including feminist issues. But also topics like the defense of democracy, the right to a dignified end of life, the impact of AI on the job market, ecology, the rise of the far right, and so on.

In men's lodges (I sometimes go as a visitor), even the progressive ones, there's very little talk of women in my experience. Except at communal meals, where you can hear the same mysogynistic remarks as in any all-male group (ewww, imho)