It’s useful to ask for people’s pronouns because it can stop you from misgendering them and enable you to correctly refer to them in a way that tallies with how they identify.
HER enables folks to declare their pronouns if they so wish, so they can signal them to others without any awkward conversation.
If someone you’re speaking to doesn’t have their pronouns visible and you want to find them out, there’s nothing wrong with asking.
Similarly, if you’re still working out your pronouns, it’s always fine to say you don’t know, - gender can be a journey.