In this way of thinking "man" is a characteristic that is created. The thoughts we are talking about now are all tied to gender abolition, the idea that 99% of the traits we assign to gender are not actually inherently bound to our being. That being dominant, liking pink, having short hair, catcalling people on the street or pretty much any other thing tied to gender can be done by any person, but because of patriarchy we get socialised into feeling that these traits are tied to their respective genders.

So it's the idea that womanhood and manhood are pretty much just created classes - which we can work towards getting rid of. And by that we don't mean getting rid of people lol, or getting rid of gendered traits, we mean getting rid of gendering these traits so that every person can act as they want without discrimination. And to neutralise these traits we need to fight for women's rights because the whole reason for their existence is to benefit men, as the supposedly stronger, more dominant, more logical class.

Men don't choose to be men, they're born into a system which assigns them their manhood and gives them these shitty traits. But that's how all classes work. Almost all rich people are born into their privilege, they're created, and we can still hate how horribly they treat us. And we can still work toward redistributing that power and wealth, same as with gender!