MongoDB’s BSON document structure can store array data types. In order to interpret that data, the user has to decide how they want those multi-value fields to be displayed.
Column-wise array expansion takes an array of values and expands them into multiple table columns creating a number of columns equal to an array specific number set by the user. If there are multiple column-expanded arrays in the same document, the combined number of new columns is appended to the end of the table with their respective array indices and the original columns are removed.
To use the column-wise expansion feature, select Column-Expanded Array in the Structure drop-down box.
The corresponding Column Count text box will be enabled and the user can enter the number of columns for the plugin to generate as columns for that array.