We translate it directly: 春秋时代: Spring and Autumn Period (or Era) (777 - 476 BC)
Most C-E dictionaries don't distinguish between 春秋时代 and 春秋时期. However, as a standalone word 春秋 is also taken to mean "all year," "the four seasons," or simply "spring and autumn" (as times of the year, versus a time in history).