"The men and the women are happy."
Translation:הגברים והנשים שמחים.
I am not sure it's grammatically incorrect but it doesn't sound natural.
In Hebrew we don't use to verb "to be" before a description, so saying that would sound something like: "The men and the women they are happy" to a Hebrew speaker.
If you put a comma, as in:"הגברים והנשים, הם שמחים" (the men and the women, they are happy) that would make perfect sense however.
No no, a comma is not needed in this case since the word הם acts as a special part of a Hebrew sentence called: אוגד It unites the subject and the object. Sometimes it can be omitted without any "damage" to the sentence. Examples:
הילדה היא יפה = הילדה יפה. The girl [is] beautiful
פירות הם מתוקים = פירות מתוקים. Fruits [are] sweet