That is a question so broad, you can fill multiple college classes with it.

On a (very) high level: Information is stored as a string of 0s and 1s, which is sent to the CPU, which then performs different actions on this string, like "add the value on position 1234 with the value on position 1212" or "write 10 to position 12345" or "repeat until the value in position 123 equals 0", etc.

These instructions come as a string of 0 and 1 as well, and once they are finished, the end product is then written back into memory or passed on to other parts of the computer, like display, external memory, WiFi connectors, ...