悬赏 is a separable verb (离合词) meaning to offer or post a reward, typically for information, a lost item, or solving a problem. The verb-object structure 悬 ('to publish/offer') + 赏 ('reward') can split: you can insert aspect particles like 了 or 过, or a measure word like 个, between the two characters — e.g., 悬了赏 ('offered a reward'). The reward is usually for a specific purpose introduced after the compound.