I honestly don't understand how someone can be sexist. I have never thought lesser of the people I've worked with because of gender. I don't know if this is too

I honestly don't understand how someone can be sexist. I have never thought lesser of the people I've worked with because of gender. I don't know if this is too personal but would you mind talking with me to explain what it's like. ive worked work many females in the past with no issues besides personalities. I just want to really understand and empathize. feel free to reach out at jbhatab@gmail.com if youd be so kind