Template blocks work similarly to Custom variables, except that you visually build each repeating block in the editor. You configure everything in your account under Settings – Template blocks. Template blocks can also be combined with Custom variables.
Ready-made template blocks, such as headers, footers, or product blocks, are available in the template editor under Saved. You can easily drag them into the email body. As with custom variables, if you need to make any changes later, you can manage all updates from one place (Settings – Template Blocks). Changes will automatically be reflected in all your templates.

Jaroslav Bouška