What is NVRAM (PRAM)

This utility will delete all the cached kexts, the prelinkedkernel file and also will reset the NVRAM (PRAM) of your Mac.

NVRAM (nonvolatile random-access memory) is a small amount of memory that your Mac uses to store certain settings and access them quickly. Settings that can be stored in NVRAM include sound volume, display resolution, startup-disk selection, time zone, and recent kernel panic information. The settings stored in NVRAM depend on your Mac and the devices you're using with your Mac.
If you experience issues related to these settings or others, resetting NVRAM might help. For example, if your Mac starts up from a disk other than the one selected in Startup Disk preferences, or a question mark icon briefly appears before your Mac starts up, you might need to reset NVRAM.

Older Mac computers store similar information in PRAM (Parameter RAM) instead of NVRAM. The steps for resetting PRAM are the same as the steps for resetting NVRAM.

What is NVRAM Kextcache Cleaner?

This utility will delete all the cached kexts, the prelinkedkernel file and also will reset the NVRAM (PRAM) of your Mac.

This application will easily reset the contents of the NVRAM without having to keep the key combinaition on the keyboard and powering on your mac. This application can be useful when you have a wireless keyboard which might not work properly when your power up your mac.

How to reset the NVRAM or PRAM according to Apple

Apple suggest using the following method to reset the NVRAM or PRAM

1. Shut down your Mac.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
3. Turn on your Mac.
4. Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
5. Hold these keys until the computer restarts and you hear the startup sound for a second time.
6. Release the keys.

https://support.apple.com/en-us/HT204063