Output gets something out of the memory of the program and computer and sends it to another place, where perhaps a person, or maybe another program can access it. Output is also useful as a way of storing data. Words like "print" and "write" are often used to describe the processes involved in output. You can read this page without following the links to get an overview of the ways you can output, or you can follow some of the links to actually find out how to do the coding.
This is probably the most basic form of output. It is where you start with "Hello World" There are more complicated ways of printing, take a look at: Python Printing