NO PLS RECOVERY prevents desktop applications from sending your iOS device into recovery mode via lockdownd. Notably, this includes iTunes.
This tweak can prevent accidental updates/restores from iTunes, because iTunes will never be able to send your device into recovery in order to restore it!
In addition, it can also thwart potential thieves who have no idea how to enter DFU/recovery mode, and attempt to restore your device through iTunes when it is still booted up.
Due to technical reasons, NO PLS RECOVERY cannot prevent or modify the DFU/recovery button combinations at boot.
NO PLS RECOVERY does not modify lockdownd, a critical system file, in any way. The modifications in this tweak are being achieved solely via Cydia Substrate.