Meaning

noun a particular environment or walk of life

noun the central area of an ancient Roman amphitheater where contests and spectacles were held; especially an area that was strewn with sand

noun a large structure for open-air sports or entertainments

originBorrowed from Latin arēna (“sand, arena”), from an earlier *hasēna (compare Sabine fasēna), possibly from Etruscan.

Etymology from Wiktionary, CC BY-SA 3.0