大田 has two distinct uses: (1) As a common noun, it refers to large areas of farmland or cropland — think broad, open fields used for growing staple crops like wheat, corn, or rice. This is a concrete agricultural term. (2) As a proper noun, it is the Chinese name for Daejeon (대전), a major city in South Korea. The context of a sentence will tell you which sense is intended. Because the two meanings are completely unrelated, you need to pay attention to context — if the text is about travel or Korean geography, it likely refers to the city.