genea is a Greek word that is sometimes translated as "age".

Strongs 1074 genea ghen-eh-ah' from (a presumed derivative of) 1085; a generation; by implication, an age (the period or the persons):--age, generation, nation, time.

A generation is generally considered to be a period of 40 years (Numbers 32:13) but it depends on how long the people live(d). Adam and Noah lived much longer than people now.

Some believe that it is 70-80 years (the lifespan mentioned in Psalms 90:10) others believe it to be 100 years (Genesis 15:13-16).

It is NOT any exact period of time. Nevertheless, it is frequently translated as "age" in our Bibles.

The "end of the age" would be the end of the generation - a time period between 20 and 100 years.

"Ages" in the following text is "genea" and means generations, not eons.

Ephesians 3:5
Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;