The last line of chapter eleven is a two-part formula that has been translated in more ways than almost any other sentence in the book: what is there gives the benefit, and what is not there gives the use.
The two words at issue are ordinarily rendered as advantage or profit, and as function or use. The first has a commercial edge in classical Chinese and turns up elsewhere in the book in exactly that sense, in chapter nineteen where profit is to be discarded, and in chapter fifty-seven where sharp instruments produce disorder. The second is the standard word for what a thing does.
Read tightly, the line says that the material of a thing is what makes it worth having and the emptiness in it is what makes it work. That is a distinction between value and function, and it is not a dismissal of either half.
Read loosely, and this is how the chapter usually travels, it becomes a general endorsement of emptiness over substance, which the chapter does not say and the three examples do not support.
The difference matters for how the whole book is read. There is a version of the Tao Te Ching, popular and not entirely groundless, in which everything solid is suspect and everything empty is preferred. Chapter eleven is regularly cited for it, and chapter eleven is in fact the passage that most carefully keeps both terms.