A typical example of how it gets applied might be a web server, where each HTTP request is handled by its own process, and potentially delegating multiple tasks concurrently to other processes in the background which handle queuing and executing work associated with that request. You might have pipelines of processes, each responsible for some specific task/transformation before handing off work to the next stage in the pipeline. On top of that Erlang/Elixir provide supervision, where components of the system are started/monitored by a special process type called a supervisor, which will restart its children when failure occurs, and if a set of conditions fail, will itself be restarted by its parent supervisor. So your application ends up structured as a tree of supervisors and worker processes, where components of the application are branches of the tree, and can be isolated from the failure of other components.
Hopefully that helps give you an idea of how the model plays out in practice. I would definitely recommend playing around with either Erlang or Elixir, they are a lot of fun, and it really changes the way you think - at least it did for me.