Imagine yourself as a male in line at the grocery store. The checker asks, "Will that be all today, ma'am?" Or consider the same situation in reverse, with a female being called "sir." It's an uncomfortable situation, right?
For people in the LGBTQIA community, this uncomfortable situation can happen every single day. Using people's preferred pronouns is an easy way to make them feel more comfortable. And all you have to do is ask!
Assuming someone's pronoun preference is as bad as guessing whether or not someone is pregnant. So educate yourself about the different pronouns people can choose, and make sure to ask--"Which pronouns do you prefer?"
Also check out this information about the grammar of genders: