RemixIconEx.System.subtract

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

subtract(icon_css_class \\ "icon")

iex> Elixir.RemixIconEx.System.subtract()
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" class="icon">
  <path d="M5 11h14v2H5z" />
</svg>

example usage

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