Geralt appreciates that she doesn't require his input on her hat purchase-- he doesn't know what a girl would want in a hat to begin with, nor what would be considered fashionable. If Jaskier were here, he'd be able to give her all kinds of advice as to what she should buy to compliment her best, whether she liked it or not. All Geralt can tell is that what she gets is within acceptable bounds of practicality-- it casts sufficient shade and appears to be sturdily made. That makes it as good as any other hat to him.

She does ask him about any plans that he has for the fair, and that's an equally difficult question. Usually, his answer would be something along the lines of 'drink heavily and make sure that Jaskier doesn't stick his cock in the wrong person', but there is neither alcohol nor bard here. Nor is he being run out of town for being bad luck, so really nothing here is like what he expects.

"I had no plans for the fair," he says. "I don't attend them very often."

Because of said bard and his overzealous cock, or because of the aforementioned running off. And when he does get to stay for a festival, his goal is mostly to remain unnoticed and unbothered.

"You can go back to your swimming. I interrupted you."