There doesn’t seem to be a consistent definition for this. It’s not an organized demonination.
From Got Questions:
Bible churches are those which profess to adhere to the Bible as their standard of faith and practice. However, they are of no particular Christian denomination (non-denominational), so there is no formal prescribed belief system to govern them.
It goes on to say this:
Some Bible churches originate from denominational pastors or groups who find themselves differing from the traditions within their denomination
Most “Bible churches” seem to be independent, so they might have been breakaway churches from another denomination.
Compelling truth notes this:
Due to the conservative nature of Bible churches, they are usually considered evangelical churches. […] Another distinctive of many Bible churches, at least older ones, is an emphasis on a literal interpretation of Bible prophecy.
Why I Looked It Up
I was talking with someone, and they mentioned they went to an “independent Bible church.” I had heard the phrase, but was curious if there was any formal definition.