Basically, tag_options() will create a set of html tag attributes from a hash:
tag_options({"id" => "cart", "style" => "color: black"})
will give you:
id="cart" style="color: black"
which is convenient to use in a tag:
<div id="cart" style="color: black">
stringify_keys is a method for hashes that converts any symbol keys to strings. For example {:id => "cart"} becomes {"id" => "cart"}
Hope that helps,
Steve