This template usually takes two parameters, like this:
{{help other| Help page text | Other pages text }}
If the template is on a "Help:" page, it will return this:
Help page text
If the template is on any other page, it will return this:
Other pages text
A typical usage case could be to make it so that a template only adds a category when on help pages. Thus not adding other pages that just show the template. Like this:
{{help other|[[Category:Some help page category]]}}
Or to warn that a template should not be used on other pages:
{{help other|| This template should only be used on help pages. }}
Note that in the first case above the "other" parameter was not used, and in the second example the "help" parameter was left empty.
For testing and demonstration purposes this template can take a parameter named demospace.
If it has the value help it returns the help page text.
It if has the value other or any other value such as the name of some other namespace it returns the other pages text.
If the parameter is empty or undefined, the actual page type determines the result.
Like this:
{{help other| Help page text
| Other pages text
| demospace = help
}}
No matter on what kind of page the code above is used it will return this:
Help page text
You can make it so your template also understands the demospace parameter. That means you can demonstrate the different appearances of your template in the documentation for your template. Then do like this:
{{help other| Help page text
| Other pages text
| demospace ={{{demospace|}}}}}