Enable Filter by Group at Customize Theme > General settings > Sidebar in Collection Page > Filter, choose "Filter by Groups"

1. Using Group Filter Tag

Add product tag with format Group_Tag Name. Know how to add a product tag here: https://help.shopify.com/manual/products/add-update-products#add-or-remove-tags

Group is filtered group; tag_name is value.

Exp: Brand_Canon; Focal Length_18 - 55mm; Resolution_12 MP will show filter Brand; Length; Resolution

2. Setup Group Filter tag for all products

- Follow the steps below to enable group filter like the image below.

  1. Define your groups. The groups are Brand, Focal Length,  Resolution

  2. Export your products into a CSV file. Read more about import export product: https://help.shopify.com/manual/products/import-export/export-products
    (If you are creating new products, you can skip this step)

  3. Edit your CSV file. Prepend all existing tags with what group you want them to be in, with the format Group_Tag Name.
    Based on our image at the top of this page, we would have tags like Brand_Canon; Focal Length_18 - 55mm; Resolution_12 MP
    The left side of the underscore is the group name, and the right side is the tag for the product. Spaces can be included on either side of the underscore.

  4. Save your .csv. file and import the products back into your store. Make sure you check Overwrite existing products that have the same handle when uploading the file to prevent duplicate products from being created.