Working with a Student I Can't Understand

Working with a Student I Can't Understand One of my friends works at a school for adults with disabilities. As a substitute teacher I can work wherever I want, but I like her students a lot, and the school is a very small very warm environment for subs and other faculty. In short-- I'm there whenever I can be but that isn't all the time. I'll be here for the next few weeks and a new student we have, we'll call her May, has a stutter. I can't tell if it's a mix between her stutter, the fact that we have to wear masks, and potential other speech issues she may have that I'm unaware of since I'm not an official employee, but I really struggle to understand her. I know enough to make eye contact, not let other students speak over her or finish her sentences for her, I don't let anyone guess her speak or anything. But, I don't know how to ask her what she's said without embarrassing her. It seems like it takes a lot out of her to speak out e.g. answering a question in front of the class, but it seems like a lot of us struggle to fully understand what she's saying. How do I help myself and others better understand her in a way that doesn't cost her or embarrass her?