The Related Products module is in the WooCommerce modules category, which appears only when you're editing a Singular-type layout in Beaver Themer and you've assigned a single product page as the location.
This module displays related products using standard WooCommerce functionality, which pulls products from your store that share the same tags or categories as the current product. If there aren't any categories or tags specified for a product, the module is not displayed in published output. If you preview a product in the Themer layout that doesn't have any related products to display, you'll see the placeholder
This module has only an Advanced tab, on which you can customize margins, responsive layout, visibility, animation, and assign an ID or class name.