It was written in Hebrew. If you want me to repeat, though yowm can be interpreted as an era, the description of day and the next day by saying the morning came, evening took place, then morning came and it was a new day, shows that it is a day as we know it, not an era. But if you want you could argue the way you please. No problem. But you dont have to get into argument mate, I asked for your explanation.
How did the Hebrews determine these days? If you read Rashi's commentary, he speaks about the causation of division between day and night. He says "This took place after the primeval (divine) light was conserved for the righteous; but during the first seven [another reading is “three”] days of Creation the primeval light and darkness functioned together both by day and by night." which has no indication of a day being an era, but rather that there was a time that before the separation of day and night by light and darkness, both functioned together throughout the day. And after God separated it, night and day is divided by light and darkness, and evening and morning is rendered by darkness and light. Thats why it seems like a normal day, not an epoch which would contain millions of Nights and days, vis a vis, "days" as we know it.
Rashbam says this - "“And it was evening, and it was morning, a second day” – the day inclined toward evening, after which was the morning after the second day, behold, the second of the six days spoken of by the Holy One (praised be He!) in the Ten Commandments, and now the third day began that morning."
I hope you understand.