This is the most common type of IP address you're going to be working with. It's a standard that has been around for decades. I love the quote from Wikipedia above, especially the part about there being 4.2 billion IP addresses. The reason I find this little fact interesting is because we've run out of addresses. In short, when the standard was designed it was thought that there would never be a need to have more than 4.2 billion addresses. How wrong they were.
When you're (eventually) working in AWS you'll be using IPv4 addresses 99% of the time. You'll create VPCs (Virtual Private Clouds - a private network) and be using IPv4 to define the address (private) space. You'll divide the VPC up into subnets, again using IPv4.
You've now been exposed to IPv4, above. For now simply understand what it looks like, what the format is and how we use CIDR ranges to break larger networks into smaller ones.