It's this passage, about how you're supposed to brew it -- I want to make sure I'm not misreading it, since potions can be really finicky about how they're prepared.

[ Better to be careful than to let it blow up on them, right?

She's holding up the instructions in question, indicating where she's having trouble understanding since it just seems worded poorly for her. Hopefully he can at least clear up that much so that she can brew the potion well... ]