AWS Systems Manager (formerly Amazon EC2 Systems Manager) is a unified interface that allows you to easily centralize operational data and automate tasks across your AWS resources.
AWS Systems Manager is a agent that can be installed and run on EC2 instances allow has various capabilities like running commands on these EC2 instances, help push data to Cloudwatch etc. Do take a look at http://docs.aws.amazon.com/systems-manager/latest/userguide/what-is-systems-manager.html for more info.