Left sidebar has 2 main content: That are: The Sidebar as column - It synchronizates with the content of Service module at the main menu. Below that is the brochure.

Let's watch the Menu Service on the frontend, you can see the synchronization between them.

Step 3: Editing module "Brochure":

Below the Menu service is the Brochure:

In backend Administration, you can find out menu "Brochure" by go to: Extension ->> Module -> Then search for the name: "Brochure"

Then you can add/ edit the content for the link of menu brochure:

Let's take a look the result at the frontend: