Link to chapter - https://serverless-stack.com/chapters/what-is-aws-lambda.html
I am also new in AWS. But if you want to know about AWS check out this blog:
There is a need for update in the statement, on URL https://serverless-stack.com/chapters/what-is-aws-lambda.html
The execution duration means that your Lambda function can run for a maximum of 300 seconds or 5 minutes. This means that Lambda isn’t meant for long running processes.
I guess someone missed to update 300 Seconds (5 minutes) to 900 seconds (15 minutes)
Please update as just above it says 900 seconds (which is correct) on same page.
Thanks for letting us know!