A sawmill is a factory — often a noisy plant or big shed near a forest — where trees that have already been cut down are sliced into boards and planks you can build with. The mill part does not mean a place that grinds grain. In English, mill also means a works where machines do one job at scale; a sawmill’s job is sawing. Before big mills, people sawed by hand; the mill turned trees into a product you could sell as lumber. Towns that grew around timber still carry sawmill in place-names. A verb “to sawmill” exists but is rare; almost always you will meet the noun.