Troops deployment is sending your troops out of the base for any reason. 

-Deployment slots are the number of legions you can send outside your base at the same time.
-Troops Deployment capacity is the maximum number of troops in one legion.

You can increase the Deployment slots by doing the following:
-Conducting technology research in the research institute concerning the troops' deployment slots, such as "reserve troops." 
-Reaching VIP level 8 and activating it.
-Exchanging all 6 storm suits equipment.

You can increase the troops' deployment capacity through the following:
-Upgrading the Logistics Center.
-Activating and upgrading your VIP level.
-Increasing your Honor level.
-Conducting Technology research in the Research Institute concerning the troops' deployment capacity.
-Use deployment limit to increase items from your backpack.
-Activate base protection by clicking on your base on the world map. You can get base protection from specific events only.