Upon unlocking the Combat Unit, you will also unlock Dispatch Missions. These missions are not ones that you personally go on, but instead send your personnel in the Combat Unit. All Dispatch Missions share a few things in common, with the first being the difficulty, which is shown as a letter grade. This only really says that you will need strong troops of your own, depending on the letter shown.
Another thing is the number of troops the enemy combat unit will have, along with their quality, which is the main stat you should pay attention to, as this directly determines what the success rate and probability of your troops’ survival is when sending them out on that particular mission. Speaking of which, both of those are shown on the same screen.
The rewards you can receive for doing these Dispatch Missions are shown in the bottom left, although you may receive other rewards than what’s there. Important Dispatch Missions have a yellow dot next to their names and generally reward you with new Emblem Parts or Blueprints. You can also temporarily disable some of the things that enemies use to adapt to your playstyle with Dispatch Missions. Also, some of the later missions will require you to have vehicles and/or Walker Gears, so you’ll need to extract some later in the game.
There are two kinds of Dispatch Missions, offline ones and online ones. The offline ones will require you to be actively playing the game in order for it to play out, while online Dispatch Missions will count down even when you’re not playing. Note that the online missions tend to have a very long timer, so they might not be worth the effort to send out troops for them.