Q: Are the 6 days of Creation mentioned in Genesis literal 24 hour days?
Answer: The Hebrew word "yom" is translated day in the book of Genesis. Just as our English word "day" can have different meanings based on its context, so can the word "yom."
For example, if I were telling a story about my childhood I might use the phrase “back in my day” to describe the period of time when I was a child. But obviously I wouldn’t be talking about a single day—even though I used that word. Again, you tell whether I mean a single day or something else by listening to the context of what I’m saying.
It’s the same thing with the Hebrew word “yom.” So when we look at the context of how that word is used throughout the Old Testament we find that "yom" is used to desribe a 24 hour period 1,109 times. On the other hand, there are about 9 instances of “yom” being used to describe something other than a single day.
But here are some keys to understanding how this Hebrew word should be taken: every time "yom" is used with additional terms like “evening” or “morning” or when "yom" is used alongside a number, such as "40 yom" (40 days), it always refers to a 24 hour period of time. And that is exactly how it is used in the Genesis Creation account. Note the example below::
And there was evening and there was morning, the fifth day. Genesis 1:23 (ESV)
You’ll notice in the verse above, the word “day” is accompanied by both a reference to evening and morning as well as a specific number. (This pattern of clarifying the word day is repeated over and over within the Creation narrative.) This all means God went out of His way to emphasize that the word “day” in the Creation account refers to a typical 24 hour period.
Frankly, the only reason people interpret this word as describing something other than a 24 hour day in the Creation account is so they can hold to the idea of an ancient earth that is billions of years old in keeping with modern Evolutionary thinking. I tell people they can believe that the earth is billions of years old if they want to, but don't expect the Bible to corroborate that opinion.