This girl I talked to said she used to talk harshly towards guys. I notice a lot of women are like this. Why?

That is considered a prejudice. She probably had a man do something bad to her like maybe dump her or something and it has made her have a negative attitude towards all men. It's not right to be that way but a lot of people do this. She should look at each man individually and get to know them and then judge whether she likes them or not.