1. A lot of people think intersectionality just means "I support gay people *and* Black people," when that's just the tip of the iceberg of the theory. It also explains *how* oppression functions. For example, a Black woman faces both racism and misogyny. However, that's not it.
2.The misogyny that a Black woman faces is augmented by racism, that's why it's often called misogynoir. A Black woman experiences misogyny differently than a white woman, and experiences racism differently than Black people of other genders. So what does that mean for activists?
3.Well, it means that you can't isolate racism from sexism from homophobia because they all intersect and alter each other. The racism a cis Black woman faces is different than that of a trans Black woman because it's augmented by transphobia.
4. All types of oppression and bigotry interlock in these ways. That's why you can't prioritize one type of oppression (like classism) over all of the others. If you're not thinking intersectionally, you're only helping the most privileged out of the group you're trying to help.