{{tl}} is the sister template to {{tls}}. It allows you to easily refer to a template inline. The long way round is to type
{{[[:template:template name|]]}}
This is far easier. Just type
{{tl|template name}}
and you're done. This is template is especially useful on talk pages or in the forum where you're discussing how best to edit a template.
If you need to indicate substitution of a template, use {{tls}}, instead.
Example
imagine the following snippet were posted to a forum thread:
- Our infoboxes have far too many fields. -- User:Example
- Perhaps, but I think {{infobox CD}} could be improved by adding a field for the long-form ISBN number. -- User:Sample