If you have trouble understanding what your CPU, RAM, and Hard drive are, hopefully it'll become clear with the analogy below.
Think of your computer as the kitchen in a restaurant.
The Central Processing Unit (CPU) is similar to the chef of the restaurant. The faster the chef prepares the food, the faster the food will be served.
The Random Access Memory (RAM) can be thought of as the stove-top and counter space where the chef prepares all of the food. The more stove-top and counter space available, the more dishes the chef can prepare at the same time. For example, a stock can be brewing while bread dough is resting and a fish is being prepared. If there isn’t enough space, then the chef is limited on how much work can be done at the same time. The more dishes or ingredients involved, the harder it is to fit everything on the stove-top and counter - this is what a program that uses a lot of RAM looks like.
The Hard Drive is similar to the refrigerator in the kitchen where all of the ingredients (files) are kept. Whenever an ingredient is needed, the chef can search the refrigerator and retrieve it. If there isn't enough space in the refrigerator, then the chef can decide to install another one or throw out some of the existing ingredients to make more room.
