In order to add context, information or picture credits to your images you can add captions.
When you add your image, whether it's in a Title, Text Over Media or Scrollmation section or inline in a text column, you'll notice you can add your caption underneath the image. You can have the same caption for desktop or mobile, or you can choose to have a different caption for each. (E.g. You may want to choose a smaller caption for mobile due to the smaller screen.)
When you highlight the text, you'll see a number of formatting options, such as bold, italic, superscript and subscript.