Many interfaces are composed of repeated interface elements. For example, your Twitter feed is made of repeated tweet elements and repeat is made based on tweets data.
To repeat an interface element, you need a data collection to repeat over.
In your pages, you have two options to repeat an interface element:
Click on the plus icon in "Dynamic Properties" section. This will show a window where you will select "Repeat" to add a new dynamic property to the element. Then another window will appear for the selection of the repeat data collection. Choose a variable of type list or a data collection retrieved from the data model to iterate on.
Click on "Repeat Element". It will show the same window than in the previous option.
You can remove the "Repeat" property of an element either from the interactions panel by clicking on the "Trash" icon of the dynamic property or with the context menu by clicking on "Stop Repeating".
Once an element is repeated, you have access to local data for this element with the repeated item information and the index of the repeated element among the collection. These 2 informations will be available in the Data Mapping Tool in the section "Variables & Local Data".