Heroku Enterprise is part of the Salesforce Platform, a multi-cloud app platform. That’s quite a mouthful! We just mean that the Salesforce Platform ties together many tools and services into a cohesive platform that you can use to build amazing applications.
A PaaS abstracts away the complexity of building and running infrastructure for applications. Using a PaaS allows you to easily create load-balanced collections of containers that run your software. You can think of those containers just like shipping containers that hold all the code and resources needed to run your application.
Trailhead – https://trailhead.salesforce.com/modules/heroku_enterprise_baiscs/units/hello_heroku