Did you know that computers talk in 1s and 0s? It's called binary. That's because computers are made up of transistors that are either on or off.
Programs are a set of instructions that tells a computer what to do. It would be a lot of work for us to write a set of instructions using binary. Instead we use programming languages like C, C++, Scratch, Ruby, Python, Java, JavaScript, etc. Why are there so many programming languages? Each one is designed to provide us with the instructions to make it easy to write different kinds of programs. Some make it easier to write games, create websites, organize data, or do fast calculations.
In the past we've done "block coding" with Scratch Jr., Scratch, Spheros, Lego Robots, and Hour of Code. Block coding is fun and easy to learn. Today you are going to be introduced to Python, by writing some mobile app games. Python is text coding. Text coding has many of the same programming concepts like loops, events, conditionals, etc. But it allows you to create more complex programs that run faster.
If you are interested, here is a video that describes how computers talk in binary: