In Peter Scholze's perfectoid spaces, Almost mathematics, I have difficulty understanding the sequence of localization functors
$$ K^{\circ}-\textrm{mod}\rightarrow K^{\circ}-\textrm{mod}/(\mathfrak{m}-\textrm{torsion})\rightarrow K^{\circ}-\textrm{mod}/(p-\textrm{power torsion}), $$ which says that it is the functor of passing from an integral structure to its generic fibre.
Here are my questions: What do ''integral structure'' and ''generic fibre'' mean in this context? Why $K^{\circ}-\textrm{mod}/(\mathfrak{m}-\textrm{torsion})\rightarrow K^{\circ}-\textrm{mod}/(p-\textrm{power torsion})$ is a localization functor? And why $K^{\circ}-\textrm{mod}/(p-\textrm{power torsion})$ is equivalent to $K-\textrm{mod}$?