Soft commodities are those that are grown and harvested, in contrast to resources obtained by mining or extraction, such as gold and crude oil (hard commodities). Some explanations, such as the StoneX glossary, also include grains such as corn, wheat, and soybeans.
This site uses the term for sugar, coffee, and similar crops, separate from grains. For example, the Coffee C futures of ICE Futures US have a specification in which each deliverable origin carries a premium or discount.