RemixIconEx.Document.book_2

You're seeing just the function book_2, go back to RemixIconEx.Document module for more information.
Link to this function

book_2(icon_css_class \\ "icon")

iex> Elixir.RemixIconEx.Document.book_2()
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" class="icon">
  <path d="M21 18H6a1 1 0 0 0 0 2h15v2H6a3 3 0 0 1-3-3V4a2 2 0 0 1 2-2h16v16zM5 16.05c.162-.033.329-.05.5-.05H19V4H5v12.05zM16 9H8V7h8v2z" />
</svg>

example usage

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