Exactly what the name implies...they seal bales, (bags), and identify the contents.
They have been used for centuries in many countries as a way to identify products, type, length, volume and such.
They have been used on reams of fabrics, paper, all kinds of things and in this country the bulk of the ones found here seem to be bale seals.
Large bags of grain or other produce where these seals not only keep them closed with wires that are usually attached to it or an attached piece that is simply bent around the bag fabric and the numbers and symbolizes are here to identify dates, volumes and contents.
They are still used today and are attached to tags, pipes and other things.