qbit stands for “quantum bit”. In classical computation one uses bits for computation whereas qbits are used in quantum computation.

A bit is used in classical computation to carry information. It is an electrical state with two levels, for instance 1 Volt and 4 Volts. At each state is associated a numeric value: 0 or 1. This is the basic of binary numeric system.

In computers, classical microprocessors are running billions of operations using bits every second.
Therefore your computer encode all values into a series of bits. For instance the value 7 is encoded as follow in a byte (a byte is a set of 8 bits):

0 0 0 0 0 1 1 1

I won't explain how to encode and decode values from mathematical value to binary value, someone else already did that better:
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You'll need to be ease with this to understand what follows.