Kiloware is a term for packages of postage stamps sold to stamp collectors by weight rather than by quantity, often in kilograms, hence the name. Kiloware usually consists of used stamps on paper from mail clippings, although off paper stamps may also be sold as kiloware.
Their worth depends on many factors. You should expect to get a number of duplicates. Good for the trader, cancel collector, individual flyspecker. Some sources are better than others. Sometimes it can be a good way to get recent used stamps.
Overall it sounds like a lot of hard work and a bit of a lottery. But then, that’s the fun of stamp collecting, of digging in to find hidden treasures.