I am trying to add a span tag inside a tags on the sub navigation on the second level on the page url below.

I have only been able to find solutions to do this to the main navigation and children and grandchildren navigation.

How would this be possible with php of jquery?

http://satbulsara.com/luke-irwin/rugs/new-in/fishy/

Try something like this...

DEMO: http://jsfiddle.net/HgkLu/

$('.page-item-173 > ul > li > a').wrapInner('<span class="abc" />');