
The AWS global infrastructure consists of 24 regions and 77 availability zones. Regions is a geographical area like Stockholm, Sweden or Tokio, Japan, while availability zones are data centers - buildings filled with rows of servers. Each region consists of 2 or or more availability zones. For example Europe contains Stockholm, London, Paris and more. An availability zone (AZ ) may consist of different buildings, but they are physically close together. Each zone is separated by a meaningful distance, but each zone are typically within 100 km of each other.
Every AZ also contains edge locations. Edge locations are endpoints for AWS and are used for caching content. They typically consist of CloudFront which is the Amazon CDN network. There are many more edge locations than regions, and worldwide there are over 215 of them.

On top of the AWS global infrastructure there are a lot of different services. They are all managed through AWS management console. The services are grouped in different categories.
In order to pass the exam you will need to know some services types concerning