This is the 3483rd most frequent Japanese word.
石炭
Coal.
Here, '石炭' is used as a noun to denote 'coal' as a subject in a factual statement about its categorization as a resource.
石炭は化石燃料の一種です。
Coal is a type of fossil fuel.
In this sentence, '石炭' is utilized within an action phrase where it acts as the direct object being burned to obtain energy.
石炭を燃焼させることでエネルギーが得られます。
Energy can be obtained by burning coal.
Here, '石炭' modifies '産業' (industry), forming the compound '石炭産業' which explains the type of industry, indicating its importance in an economic context.