"The lions are happy."
There are masculine nouns in hebrew that end with "ות-".
For example: "אריה/אריות", "שולחן/שולחנות", "אב/אבות"
so do animals only have one gender per species? are there female אריות and if so, are they שמחות or שמחים?
lions are one of the few examples of animals where the female of the species has a different name
The female lions are happy = הלביאות שמחות
interestingly, there are multiple synonyms for the male lion, one of which is לביא
That would be " The Lions, they are happy " (also הם, not הן)