In serverless development, the shift of focus is towards the small functions of the application rather than the deployment of entire application at once.
This is the core advantage. Serverless is scalable in nature and you get the maximum scalability with a proper planning. It is secure inherently and abstracts the security on a bunch of configuration options. You need to pay only for the usage time and this could bring the cost down significantly.
In most of the use cases, we use a bunch of AWS services for serverless architecture. These include AWS Lambda, Amazon API Gateway, Amazon DynamoDB, Amazon Cognito, and Amazon Amplify.