For understanding the concept of functions being executed as/inside containers, we need to properly understand the concept of containers. To cite the definition of a container from the Docker documentation (https://www.docker.com/what-docker):
A container image is a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run it: code, runtime, system tools, system libraries, settings.
What is available for both Linux and Windows based applications; containerized software will always run the same, regardless of the environment.
Containers isolate software from its surroundings (for example, differences between development and staging environments) and help reduce conflicts between teams running different software on the same infrastructure.
So, the concept of containers is that they are self-sustainable isolated...