what is a magnetic lure module

A Magnetic Lure Module is an item in Pokémon Go that can be placed on top of a PokéStop to attract Electric, Steel, and Rock-type Pokémon to the location for 30 minutes. It can also cause some Pokémon to evolve, such as Magneton and Nosepass into Magnezone and Probopass, respectively. Magnetic Lure Modules can be acquired through the in-game shop, as individual purchases or as part of various bundles, or by completing Special Research stories or Timed Research tasks.