In which AWS service you don't have to take tension about managing the servers, managing infrastructure, and provision to run the code?

Amazon Web Services, Inc. (started in 2006) is a subsidiary of Amazon that provides on-demand cloud computing platforms and APIs to individuals, companies, and governments, on a metered, pay-as-you-go basis. Oftentimes, clients will use this in combination with autoscaling.

Basically, it is a cloud computing provider and the main profit source for Amazon.