Visit your application - what's process type and dyno running?

[MarysiaLowas]

In the Deploy chapter, in the Visit your application section, there are two paragraphs there are not clear for me:

You’ve deployed your code to Heroku, and specified the process types in a Procfile. You can now instruct Heroku to execute a process type.

Let’s ensure we have one dyno running the web process type:

You lost me there.

Can anyone maybe add a sentence or two to explain what's process type and dyno? Or maybe to phrase it differently so it's easier to understand?

Thanks a lot for anyone that will! :)

[bmispelon]

Confession: I have no idea what a Dyno or a process type is.

I read through https://devcenter.heroku.com/articles/procfile and tried to explain what I understood in #105.

Feedback welcome (both on the style/spelling/grammar) and on whether what I wrote is technically accurate.

Thanks!