A classical bit is a switch: off or on, 0 or 1. Every photo, message and spreadsheet on your computer is billions of those switches.
A qubit is not a switch. It is closer to an arrow pointing somewhere on the surface of a globe. Straight up is 0. Straight down is 1. But the arrow can point anywhere else too - at the equator, or halfway between.
That "anywhere else" is the whole trick. A qubit holds a direction, and a direction carries more information than a switch position.
The catch is that you cannot read the direction. When you measure a qubit you get back one bit: 0 or 1, nothing more. Where the arrow was pointing only changes the odds of which one you get. Point it near the top and you will almost always read 0. Point it at the equator and it is a coin flip.
So a qubit can hold a rich state, and measuring it collapses that state down to a single bit. Quantum computing is the art of arranging things so that the bit you get back is the answer you wanted.