[ShinyRice]

Luminosity is the number of particles (in the LHC's case, protons) flowing per unit area and unit time.

Additionally, integrated luminosity is luminosity integrated over time, and is just the number of events produced per unit area. It is the main metric used when CERN releases data and shares just how many events are in a given data set; this is done such that you can take the cross section of a given event (like Higgs production), multiply it by this value, and get how many events of that type happen (how many Higgs were produced).