"Exodus 20:11.-- this verse is critical to the question of the age of the creation. It stands as an insurmountable stone wall to block every attempt to add millions of years anywhere into the Bible. Therefore, to be faithful to Scripture, Christians must reject the “big bang” theory and the billions of years of cosmological and geological history as myths.
Exodus 20:11 is very important because it is God’s Word in a special way: it was not written through Moses but rather directly on tablets of stone by God Himself.
In Exodus 20:11, God used the same Hebrew word for “days” (yamim, the plural form of yom [day]) that He used in verse nine, showing that God’s days of creation in Genesis 1 were the same kind of days (the same length) as the days of the week for the Israelites. It is doubtful if any faithful Jew ever interpreted it any other way until the idea of millions of years started to take control of people’s minds about two centuries ago.
We should note that if God really created over the course of millions of years (as most Christians around the world today believe), He could have clearly indicated that in the Hebrew. He could have used the Hebrew word dor (דּוֹר), which is translated in English Bibles as time, period, or generation.
Or He could have borrowed an Aramaic word, as He did in the books of Nehemiah and Daniel, such as zeman (זְמָ֑ן) or iddan (עִדָּן), which are translated as season, time, or period.
Or He could have used some phrase such as “after many days,” “after some years,” “after thousands of ten thousand years,” or “after years of many generations.”
But instead, God used the only Hebrew word, yom (יוֹם), that means a literal, 24-hour day, and it means that (or the light portion of a literal, 24-hour day, in contrast to night) in the majority of the 2,320 times it is used in the Old Testament."
AIG