RemixIconEx.System.filter_2

You're seeing just the function filter_2, go back to RemixIconEx.System module for more information.
Link to this function

filter_2(icon_css_class \\ "icon")

iex> Elixir.RemixIconEx.System.filter_2()
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" class="icon">
  <path d="M14 14v6l-4 2v-8L4 5V3h16v2l-6 9zM6.404 5L12 13.394 17.596 5H6.404z" />
</svg>

example usage

svg.icon {
  width: 96;
  height: 96;
}