This is the 3872nd most frequent Japanese word.
オス
"オス" means "male" (typically for animals).
Here, 'オス' refers to male animals, describing the gender of the lions.
その動物園ではたくさんのオスのライオンを見ることができます。
You can see many male lions in that zoo.
In this sentence, 'オス' is used metaphorically to denote masculinity or a male individual's expected societal role.
彼はオスとしての役割を果たす責任を感じています。
He feels responsible to fulfill his role as a male.
Here, 'オス' is used symbolically, attributing characteristics like strength traditionally associated with males to an inanimate object.