Era means a long period of time, for example it can be used to mean decades (10s of years) thousands (1000s) or millions (1000,000s) of years. It is usually used in a scientific context. Such as the Mesozoic Era (when dinosaurs lived). Age usually means how old something is. For example: 28 years is my age. What age is this wine? et cetera. But Age can also be used in the same way as Era. e.g "the bronze age", "the information age". In this context it also just means a long period of time.

age最常用指年龄，也可指某个时段时代。 time最常用。泛指时间，可演变出各种与时间有关的词。 era指一个时代。