[It takes Muffet a brief second to get it, but then she looks delighted.]

Oh, it's a little snail, how cute- I hear they're quite useful creatures.

[Admittedly, the person telling her about it had been rather timid, but they seemed very sincere despite it- Napstablook had been polite enough to let her put up one of her bake sale's advertising flyers at their farm once, and that had earned the quiet little ghost more than enough fondness from her to listen to a few stories about snails.]

If you could work out how to make a hand shape, that might help people understand even if they don't read.