Actual this is a extra line that comes up for sheet metal parts. Make a sheet metal and make BOM for it. Set the BOM to indented and you'll see what I mean. I've no clue as why it is there but it is there.
The icon stands for "Body" since this line shows the cutlist properties of you sheetmetal part body. You just don't have any values asigned. You need to open your sheetmetal part and delete the cutlist folder and deselect automatic update in order for this extra line to go away.
This is default behaviour.
Actual this is a extra line that comes up for sheet metal parts. Make a sheet metal and make BOM for it. Set the BOM to indented and you'll see what I mean. I've no clue as why it is there but it is there.