Search Elements tracking type is for tracking a URL/Business among any search element that is not organic:
Snack Pack box (top-3 maps) or Videos section.
Unlike the organic results (and the sponsored results), Google’s Search Elements appear usually on the first page, among other organic results, and has also an inner order of URLs/Businesses.
Rankings are represented by a number and a letter.
The number represents the position of the entire box on the page, and the letter represents the position of your URL within the search element’s results.
For example, when tracking a video on Google, "3 B" would mean that the Videos element box was in the 3rd position (occurring after two organic results), and your video within that search element was 2nd ("B" being the 2nd letter in the alphabet), from left to right.