Nebulous (adjective)- of, relating to, or resembling a nebula

https://www.merriam-webster.com/dictionary/nebulous

This word was found in the article by Lex Berko “What If You Could Choose Between the Fastest Route and the Most Beautiful Article” which states “But how do you quantify concepts as nebulous as beauty or happiness?”. This was located on the first page, fourth paragraph, on the first sentence.

This word wasn’t clear to me but reading the definition it was some what clear to me that the word nebulous meant something relating to. To better explain this word in the sentence “But how do you quantify concepts as nebulous as beauty or happiness?”. What this means this how can people relate to something in there life to a park or a place that they call peaceful. As well the question to ask ourselves is to compare something that we have experience to what we have in front of us.