What do the names of the eras mean?

Era – from the Latin “Aera” – the original number. The name of a major stage in the geological development of life on Earth. There are five stages of the formation of the relief, flora and fauna of the planet:

Archean era – from the ancient Greek “ancient”. The first stage began 4600 million years ago and lasted 1.5 billion years.
Proterozoic era – from the ancient Greek “first, senior” and “life”. Follows Archaeus, 2.5 billion years long, longest.
The Paleozoic era is the era of “ancient life”. The third stage of the development of the Earth, duration 289 million years.
Mesozoic era – from the Greek “mezos” – “middle”. Lasted 183 million years.
Cenozoic era – “new life”. The modern era, which began 66 million years ago.