"Vous mangez une baguette et elle mange la soupe."
Translation:You are eating a baguette and she is eating the soup.
Yes, my friend above it correct. It certainly is possible to use THE with mass/noncount nouns. It's the indefinite article A/AN that you usually do not use. (e.g. THE soup is tasty = ok.... A soup is tasty = not quite right)
However, in the case here, there is no reason to require the use of THE