"Conquest mode" refers to a type of game mode or gameplay that focuses on taking control or dominating an area, territory, or opponents. Full definition
You have ladder mode which sees players climbing a tournament ladder to win prizes, conquest mode in which you have to try and win ten matches before losing three for some great rewards and Brawl Club in which clubs of up to fifty players face off against each other. (thatvideogameblog.com)
Honestly the campaign mode feels so tacked on that I would say pass over it and head right into conquest mode where this game really shines. (thezombiechimp.com)
A compelling campaign following the 501st legion is accompanied by instant action and galactic conquest modes, alongside a multiplayer scene that was revived just last year and boasts an active community. (gamewatcher.com)