They can’t go down to the local community college and sign up for a class where they can practice explaining all of the complexities of their mental health in simple terms. They’re experimenting with what works, what is comfortable, what is confusing, etc. Give them some space to do that and know that when they are still at this uncomfortable level they trust you to be someone they want to talk to.
Don’t ruin it for them by being dismissive or not listening. They need you to listen and they need practice in telling their stories. Be the same place for that.