Imagine you need to create a super secret password that nobody could ever guess, even if they tried for hundreds of years. That's basically what a Bitcoin private key is - an extremely secret code that gives you access to your Bitcoin. To generate a secure Bitcoin private key, you need a sufficient source of randomness (or entropy) to make it difficult to guess.
During the purchase flow of your Satori Coin, you might be shown a page that asks you to move your mouse randomly until the progress bar fills up. As you move your mouse, the software is capturing this unpredictable information and converting it into the random bits needed for your private key.
The more you move your mouse (especially in unpredictable patterns), the more entropy you generate, and the more secure your private key becomes.