Android recovery is a bootable partition, which lets you apply official system updates from SD Card, factory reset your phone or wipe its cache partition.
How to enter Samsung Galaxy Tab 4 10.1 recovery mode ?
Power off your device.
Boot in recovery mode by pressing and holding Volume Up, Power Button and Home Button at the same time.
Release all buttons when the Samsung Galaxy Tab 4 10.1 screen flickers and in a few seconds the Recovery screen will appear.