A Resistance Pocket is a Powerplay-related System Signal Source specific to Archon Delaine. It is similar to a Conflict Zone, but contains ships aligned to a Power battling against a system's defense forces. At these sites, the Power is trying to prepare the system for its expansion there by eliminating resistance to its rule. When aligned to Archon Delaine, pilots will receive 10 Powerplay (bonds) per ship killed at Resistance Pockets.
To locate a system with active Resistance Pockets, check the "Expansion" tab of Archon Delaine in the Galactic Powers menu.