you first create a mask of the class you want to assess in the mask manager, then you can calculate its size.
Please have a look here: Mask Area in Senintel1 data
and here Calculating water area
you first create a mask of the class you want to assess in the mask manager, then you can calculate its size.
Please have a look here: Mask Area in Senintel1 data
and here Calculating water area