publishing off-the-shelf offerings

Hello, could someone explain to me “Unreal Engine End User License Agreement for Creators” license.
What "publishing off-the-shelf offerings " does exactly mean? Thanks!

“Off-the-shelf” is industry lingo used to describe non-custom products that are sold generally to the public, as opposed to products that are customized according to the specifications of a specific product.

Thanks a lot for your answer!