A little list of personal computer hardware abbreviations to help you to understand better.
PC - Personal Computer
CPU - Central Processing Unit
MoBo - MotherBoard (aka MB or MBD)
RAM - Random Access Memory
GPU - Graphics Processing Unit
SSD - Solid State Drive
HDD - Hard Disk Drive
PSU - Power Supply Unit
FDD - Floppy Disk Drive (obsolete nowadays)
FD - Floppy Disk (also obsolete)
ODD - Optical Disk Drive
CD - Compact Disk
DVD - Digital Versatile Disk
BD - Blu-ray Disk
OS - Operating System
Of course there are more abbreviations (like DDR, GDDR, AIO, rad, KB etc) but the above covers the basics.