This template contains simply the code
<br />, the XHTML-clean line-break. It is to be used as an inline line-break.
CRLF is a standard name for a line-break variable.
The reason this template might be useful over just typing
<br /> is because a template call can cover two lines. Thus, you can call this template with the code:
whereas a normal
<br /> can only be called with:
on one line. The advantage of the two lines is that it aids the editor, both in his reading and writing, and you can actually see the line-break that you've just inserted the code for.
The template is especially made for use inside indentation or bullet points; see the Talk page for examples.