Computers work on ones and zeroes and it is a big part how they work on inside. If we would have a look inside the computer, we will find out that computer is compiled from electric wires and circuits and those are carrying all the information inside the computer. Information which is stored inside the computer is represented by bits. If computer has more wires it makes it able to store more bits, which is represented by more complex information.
Computer works on binary number system, what is defined only by zeroes and ones. Any number can be defined by binary number system, but not only numbers, it includes text, images and sounds as well.
For the text we can assign a number to each letter and this number can be defined in binary system. In case of images, videos or any other graphics, all of them are made of pixels and each pixel has colour which is represented in RGB system by numbers. Sound is defined as series of vibration which can be visualised in graph and any wave point of the graph can be defined as a number. Higher quality of the sound needs higher bit audio.
Everything in computer works on zeroes and ones and electrical signals and in circuits behind them.