The phrase "several side missions" refers to additional tasks or objectives that are not the main focus or goal. These missions are optional and often provide extra challenges or rewards within a larger activity or game. Full definition
Along with several side missions, eager Guardians will need to obtain four Resonate Stems and hunt down Sleeper Nodes which are hidden across Mars. (allgamers.com)
The inclusion of several side missions allowed for the introduction of several lesser known villains from the Batman mythos (had any of you non-comic geeks ever heard of the Calendar Man before?). (oracleoffilm.com)
You can unlock different costumes, including Spider - Man 2099 and Ultimate Comics» Spider - Man, during several side missions in the game and each has in - game information about it as well as real - world first appearances. (gamegrin.com)