Explain why science says that Earth is millions of years old and the bible says thousands.
Bible does not say anything about the age of the Earth.
It does mention that a day in heaven
is like a thousand years and a thousand years (in heaven) is like a day (on earth). The concept of this statement is only to demonstrate the meaning of time in heaven, ie. that time is meaningless in heaven.
An apple is like an orange, but it is not an orange.
The universe itself is created in 7 of God's days, but the bible doesn't quantify how long or short is a God day.
Therefore, the time of the universe and Earth time coincides with science. Evolution is a tool God uses to create.