You can take a look at the AVR fuse calculator first:
select ATmega328p as the mcu. This will give you the complete list of fuse bits options on ATmega328p. Basically the fuse bits allow you to set the mcu clock source, bootloader sector, watchdog timer, brown-out reset, and so on. For details you really have to look at the mcu's datasheet.
Warning: be very careful if you want to re-program the fuse bits. Make sure you understand the changes you are making. It's easy to mess up with AVR chips if you program the fuse bits wrong. The common mistakes are selecting the wrong clock source, or disabling reset pin -- these can make the mcu fail to start, or disable ISP programming capability. The only way to recover is to use a high-voltage (12V) programmer. I've learned my lessons. So be careful.