Extension instead of epilogue means that at the end of this paragraph, the extension of 6 bars is formed by bass module to play the role of extension instead of epilogue.

The epilogue now often refers to the last part of a large-scale piece of music that complements and expands and strengthens the sense of termination.

Extension instead of epilogue is a musical term. It used to be a general term for the last song of a complete set of aria in Qupai music, which has the function of extending the unfinished meaning of aria. Now it often refers to the last ending part of a large-scale piece of music with supplementary extension and enhanced sense of termination.