TL;DR;

Labels allow data to be classified according to the sensitivity of its content. You can apply a label via Right-click > Details > Apply Label or when uploading a file.

How To

1. Right-click on the file you want to apply a label to and click "View Details".

2. In the column that opens on the right side, scroll to the Label section.

3. Open DESelect Data Classification section and apply the correct label. The description will explain which label should be applied.