Pseudo random numbers
Random numbers have been used in games for a very long time, from traditional card games to dice rolling in table-top games. Random numbers add a chance factor to games that make them exciting and forever unpredictable. The unpredictability of a game is exciting because it always offers a unique experience. You can introduce this randomness factor into your games with a little computer science in the form of a PRN generator.
PRNs and PRN generators are a highly researched subject in computer science, as they are central to cryptography and cyber security. If you ever look into cryptography, you'll find it heavily steeped in complicated mathematics. Luckily, Unity has a very easy method to generate random numbers. Certainly, the complexity of secure number generation isn't required for video games. Nonetheless, it is important to understand some of the theories behind what seems like magic.