I have no idea if that makes sense, but here I go.

I'm using this site to help me track my shiny odds, and I notice something called B(n,p). What is that? What does it mean, and what is it telling me?

B(n,p) is a standard notation for the binomial distribution. Without getting into the maths, it is telling you what your chance of getting a Shiny is given n attempts and p chance of getting a Shiny in each attempt.

The field below that is telling you how much higher n needs to be for B(n,p) to be at least 90%.

Well, it appears to be something called binomial distribution? It's a math thing that I don't really understand, but yeah, that's what I could find.

Hope this helps! :)