This is a fascinating question. We might like to initially start by refering to what the author herself says about the naming of this novel and how she came up with the title, before discussing how it relates to the novel as a whole:
It’s not a very interesting answer. I felt a lot of my fiction to be very essayistic, very tick-all-the-boxes, so I wanted to give this one an essay title and do exactly the opposite; be free with it, let it go its own way. I can’t explain it any better than that. My titles always come immediately to me and are never changed. I never really have a very good reason for them apart from the fact that they seemed inevitable.
So, clearly there is something instinctive about the naming of this novel, and Smith is parodying literary essays whilst deliberately rejecting the form of a literary essay in the riotous romp that follows in the novel. However, if we consider the action of the story and the various struggles that the plethora of characters face, perhaps we can relate the title to the action. If we think of beauty as the governing abstract noun of the text, the variety of characters all seem to stand in relation to beauty. There are some characters who possess it, others who yearn for it, those who embrace it and those who reject it, and lastly those who exploit it and those who are destroyed by beauty. In particular, let us remember that it is a shared love of beauty that draws the two central female characters together, in spite of the animosity between their families. So perhaps we could argue that the focus of the novel on beauty becomes a lense through which we can look at and interpret the variety of characters that fill its pages.