what does the word "denn" mean in this sentence?
Was würden Sie denn vorschlagen?
In this sentence, "denn" can be used as a flavoring particle; i.e., it is used to express added curiosity to the tone of the sentence. German has several of these words which you must memorize their (varied) meanings. Other words (which also have their own separate and more "regular" meanings include: ja, doch, etc.).