The Universe is very big place but we can only see a certain parts of it it contains the Pegasus cluster, Virgo cluster, local group (we live in the local group), Centaurs cluster, Fornax cluster, Hydra cluster.
Cluaters are massive groups of galaxies bucked to gather it may contain anything to a few dozen to few thousand. That might sound a lot but it mostly believed to be made of darkmatter.