Bootstrapping mean Booting process when the computer is switched ON. When the PC is switched ON, the BIOS ROM is activated, which in turn bring first OS related file from the boot sector of the hard disk, once this file is loaded on to the primary memory of the computer, it will fetch the next file from the hard disk. This newly loaded file is responsible for bringing yet another OS related file to the memory. Thus all required files are loaded, and the system is now ready for use. This process is similar to how the strap of a boot works, hence the process of loading OS files is called bootstrapping.
What you mean by the term Hibernate Your Computer?
Whenever you are no longer using your computer, e.g. during your lunchtime, or tea break instead of shutting down the computer you can make your computer in hibernate mode by pressing hibernate button provided in the GUI of the computer. When you hibernate your computer, the CPU runs very minimal functionality, and therefore the heat produced inside the CPU is drastically reduced. Therefore the rotation of the fan is also reduced, and the overall current consumption of computer comes down. Hence you are saving power consumption by putting the machine in hibernate mode during your rest time.
The word hibernate is originated from Biology. Many creatures like Ranahexotica and polar bear do hibernate in summer season and winter season respectively. Metabolic activities are heavily reduced in the animal during the hibernation period.