In Python (and any language that stores variables), a variable is a reserved memory location that stores a value. They are names that can be assigned a value and used to reference it throughout your code. Using a variable makes a value accessible & gives values a context/meaning concerning your code.
Variables are at the root of manipulating/processing data input for any programming language. This is just such an easy-to-follow short tutorial that sets out the concepts.
Python itself is free to use, so anyone can install it (also some links in this article about how to install it on Linux and Windows) and play around a bit with these concepts.