The WooCommerce Grouped Product type allows you to group together a selection of Simple Products. Think of it simply as a product page that displays a list of related products where users can add them all to their cart in one go.
Customers still have the option to choose products from the list, and change quantities.
First create some Simple Products as these are the only product types you can use with Grouped products.
Now create your Grouped Product, on the product editing screen set the product type to Grouped product: Product data – Grouped product
The number of panels in the Product data will lessen, click on the Linked Products tab.
In the text box next to Grouped Products start typing the name of a Product to add, and click it in the list that appears to add it to the Grouped product.
NOTEYou can only use Simple products with Grouped products.