The price of rice is controlled by the government.
Literal
Rice-price [topic-は] government [by-によって] controlled is.
米価 is 'rice price' — 米 (rice) + 価 (price). 統制されている is the passive of 統制する (to control/regulate) plus ている for ongoing state. によって marks the agent in a formal passive. A factual sentence about agricultural policy.