What is a 'Stagger'

These are successive screens (one after the other) for the same player, usually arranged in a non-linear way, with some curvature (hence the term "staggered") to facilitate the offensive player's movement and make it difficult for the defender. The idea of setting multiple screens successively is to make the defender of the screened player struggle as much as possible and accumulate small disadvantages with each screen, so that with the sum of two or even three screens, enough advantage is gained to get an open shot.