Binary does more than express numbers - through bytes, it can symbolize all alphanumeric symbols, which can then be interpreted into more complex code.
The most basic thing is a bit, up or down, 1 or 0.
After that there's a byte, 8 bits.
All numbers (255 and less), letters, and symbols can be translated into bytes that the computer can understand.
There are a lot of languages that computers can work with, and what I want you to get away from this video is that all data in your computer boils down to binary bytes.