This is about the calendar but they left out the months!

January is named after Janus, the god of beginnings and transitions

The Roman month Februarius was named after the Latin term februum, which means "purification", via the purification ritual Februa held on February 15 (full moon) in the old lunar Roman calendar.

March comes from Martius, the first month of the earliest Roman calendar. It was named after Mars, the Roman god of war

April (Latin name Aprilis) but the derivation of this name is uncertain, possibly also from pagan deities

May (in Latin, Maius) was named for the Greek goddess Maia

June is ultimately derived from the Latin month of Iunius, named after the ancient Roman goddess Juno

July was named by the Roman Senate in honour of Julius Caesar in 44 B.C., being the month of his birth, whom they granted divine honors

August was renamed in honor of Emperor Augustus, who was also accorded divine honors

September, October, November and December are simply named for numbers, being the seventh through tenth months of originally ten months in the oldest known Roman calendar.

Source: Wikipedia