Recovery Mode shows a cable pointing to a computer (or iTunes logo on older iOS). You may have entered it accidentally while pressing buttons, or the phone dropped into recovery after a failed update. Sometimes you can exit without restoring; sometimes the OS is too damaged and only a restore works.
Try the same force restart sequence as in our Apple logo troubleshooting guide. If the device boots to the lock screen, you are out of recovery. Back up immediately with i4Tools backup.
Some versions of i4Tools offer a one-click Exit Recovery Mode when the device is detected. Connect USB, open i4Tools, look for repair or recovery tools. This may work when the filesystem is still intact.
If the phone returns to recovery every boot, you need to restore iOS via iTunes/Finder or i4Tools flashing. See DFU and Recovery Mode and Firmware Flashing.