I wanna learn what exactly does revalidate do in nextjs. Does it completely recompile the page (i.e. generateStaticParams) or only update the cached data?

More importantly, I wanna know what would be the best value for export const revalidate for me? I have a e-commerce website with about 100 products (the page /product/[slug] is statically generated using generateStaticParams). So how frequently can I afford to revalildate the page till it gets too frequent?