商用 (shāng yòng) is an adjective meaning 'for commercial use' — it describes things designed or used for business/profit purposes, like 商用设备 (commercial equipment). It differs from 商务 (shāng wù), which is a noun for 'business/commerce' as a field or activity (e.g., 商务旅行 'business trip'). 广告 (guǎng gào) is a noun meaning 'advertisement'.