Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings

to show; to reveal; to expose; to let something be seen (often pronounced loù in colloquial speech)

A person's voice and countenance when speaking, often used to describe emotional reactions or the lack thereof; see also 不露声色 bù​lù​shēng​sè