You have already seen the use of the processors fact in an example. In the manifest, each fact value is available as a global variable value. That is why you can just use the ::processors expression where you need it.
You will often see conventional uses such as $::processors['count'] or $::networking[‘ip’]. Prefixing the fact name with double colons is highly recommended. The official style guide at https://docs.puppetlabs.com/guides/style_guide.html#namespacing-variables recommends this. The prefix indicates that you are referring to a variable delivered from Facter. Facter variables are put into the Puppet master's top scope.
Some helpful facts have already been mentioned. The processors fact might play a role for your configuration. When configuring some services, you will want to use the machine's networking...
