The way current computers work is that they use electricity to process information. Modern computers only use 2 states. Either no electricity is flowing (0) or there is electricity (1). This might sound complicated but it’s pretty easy. Think of a lamp. If you turn the switch off no current is flowing and the lamp is off. This represents a 0. Vica versa, opening the switch allows current to flow and the lamp turns on. This would be a 1.
You can use these 1’s and 0’s to do simple logic. For example, imagine a lamp with 2 switches along the cord. The lamp will only turn on when both switches are closed. This represents a logical AND gate. Swap the switches for electronic transistors and this is all your computer is doing. You can combine logic gates to make a circuit that can add binary numbers together, or a bit of memory, or a control unit. With a complicated enough set of logic gates you can do all sorts of math, render video, etc
Quantum computing however uses “qubits” (as opposed to our bits which can only be either a 0 or 1 ie two states), these qubits can not only be 1 and 0, they can be more like a combination of both 0 and 1 at the same time etc.
This gives us more states to work with, Ex: Now we have 0, 1 and a 0.5 which can be stored in this “qubit”, the whole computing just got faster.