燻 is an alternative, less common form of 熏 (xūn). As a noun, it refers to smoke, especially the kind produced for curing or flavoring food, or the process of smoking itself. In modern Chinese, the character is rarely used alone as a noun; it appears more often as a verb in compounds like 燻肉 (to smoke meat). The noun sense is largely literary or technical, and you will mostly encounter the simplified form 熏.