You have inserted some Structural Shape frames with Frame Generator and in the assembly BOM the quantity of these frames is set equal to the length.
- In the Bill of Material dialog click on Choose Columns.
- From the following Customization dialog, drag the column Base QTY in the BOM.
- In the first frame row, double-click in the cell of the Base QTY column.
- Click on the arrow that appears at the right of the cell.
- In the following dialog, select the “Each” under the Standard Quantity Property.
- Select the lower-right corner of the cell and drag it down to the last frame cell, applying the same setting to the other cell.
By the way, if you don’t want to apply this procedure and it is enough to display the quantity you like in the Parts List, as alternative, you can just replace “QTY” column with “ITEM QTY” one there.