The phrase "various missions" refers to a range of different tasks or goals that need to be accomplished. It suggests that there are multiple objectives or assignments that a person or a group is working on. Full definition
From there, the primary method of advancement is learning new skills through completing various missions. (mmobro.com)
This mode allows you and three buddies to take on various mission on four co-op maps. (thekoalition.com)
The campaign is where you'll spend most of your time, which has you playing through various missions either on your own or with up to three friends. (squarexo.co.uk)