It basically a Global Cloud Platform. Which allows hosts and manages the services on the internet.
It provides Infrastructure as a service. This means they provide bare servers as a service so you don't need to manage the backup and the power supply of the service
Provide Platform as a Service. You can get Java, Ruby, and PHP as a service so that you don't have to manage the software files of these applications.
Software as service. It refers to a situation or context where you have the ability or capability to send emails like ses (Amazon Simple Email Service), queuing as a service like sqs (simple queue system) and it's a cloud storage platform where you have a lot of storage option including ebs and s3.
AWS is a hosting provider which gives you a lot of services where you can run your applications on the cloud.