In this case, a 'trait d'union' ( hyphen) as its name indicates is used to link two nouns together creating a new word with a specific autonomous meaning. There are lots in the French language...
Hope this helps!
rez de chaussee or sous sol
Thank you for the comments. It seems that you just have to remember they are needed in text. When speaking you don't need to know.
Sign in to submit your answer
Don't have an account yet? Join today
Test your French to the CEFR standard