Your character doesn’t speak per say, so you usually are limited to gestures for interacting with other players.
The stone refers to a series of items thatve been around since dark souls 1 where you drop a magic stone and a voice comes out saying the line. In dark souls 1 and some others it was a rock you dropped and it broke open making sound, so the “stone” term stuck.
In elden ring it’s called a “prattling pate: ‘voice line here’”. Your character blows into it like a flute kinda and the line is spoken.
Basically the guy showed up, said “damn ur fashion is on point” then left :)