Grouped products are often confused with bundled products and configurable products. All three product types are parents of simple SKUs, so they can often be confused.
Configurable products are meant to be used for products with options such as size, color, or some other variant. Bundled products are meant to be used for products that have complex configuration options such as a computer in which they can essentially be customized into a unique product through a makeup of individual products like processors, hard drive space and more.
You can see in this example in the Magento 2 sample data set you can order a group of Yoga straps of different lengths. You can also choose the quantities of each simple SKU within the group that you want.
Creating a Grouped Product:
In the admin panel, a grouped product is very easy to setup and manage, more so than configurable and bundled because it is literally just a collection of simple products.
All you need to do is create a grouped product, fill out the basic attribute information like description etc, and associate the simple products with your grouped product in the grouped section. You can see from the screen shot it is very similar to associating products via a configurable or bundled product, however, you do not need to worry about attributes and other more complicated elements that you would with a configurable product.
Pricing is controlled via the simple SKUs, so the parent grouped product has no pricing option. Quantity is also controlled via the simple SKUs.
Once you have created your grouped product you can edit and improve the product data via descriptions etc, just like any other product to start improving sales!