减少 (jiǎnshǎo) is a transitive verb meaning 'to reduce' or 'to cut down' on something — you reduce the amount, quantity, or degree of a direct object (e.g., time, taxes, stress). Unlike 下降 (xiàjiàng), which is intransitive and describes a drop or decline on its own (prices fall), 减少 always takes an object. It is more general than 降低 (jiàngdī), which focuses on lowering a level or standard.