It depends on whether they've done a beginner's class or course or club sparring yet. For instance, have they already covered safety matters with equipment and safety with the uniform? Also ettiquette, & maybe a quick word on what the blade in question evolved from. Have they already covered en garde, advance, retreat, lunge? Have they already had an introduction to parries and attacks and sparred at the club? Are they still doing those things correctly and do they have any injury effecting that? I'd encourage them to say if they're not clear about anything.
If you don't know much about them yet it's the least awkward occasion to get each other's names and write them down. It's also an ideal opportunity to learn about any past sport fencing or HEMA experiences they have and to discuss similarities and differences at the start or end.
New people won't know and will need to have explained the teacher-student ways of doing things in a one on one, like only doing precisely what you've told them when you say when masks are on and not to ad lib hits here in their enthusiasm unless asked to. I'd be wearing armour with a first time student if I were a teacher.