What this new task does it helps to transform/transpose/flatten your JSON structure into a denormalized flatten datasets that you can upload into a new or existing flat database table.
I like the analogy of the Transpose function in Excel that helps to rotate your vertical set of data pairs (name : value) into a table with the column names and values for corresponding objects. And when this vertical JSON structural set contains several similar sets (array) then ADF Mapping Data Flows Flatten does a really good job by transforming it into a table with several rows (records).
Click through for a demonstration.