"This message is important."
Translation:Este mensaje es importante.
I was wondering also. My husband who speaks Spanish as a first language says either esta or es works in this sentence.
Esto is neuter. Este is masculine and goes with mensaje.
Esto is not used before nouns, since all nouns are either masculine or feminine.
It said i got is wro g, but then showed the correct solution as what I selected. Mensaje was available twice?