What is the detailed meaning of Bid'ah according to Imam Al-Shafi'i, please?

Innovation (Bid‘ah) is of two types: Linguistic innovation; which is every newly introduced thing without a prior example, whether it is praiseworthy or blameworthy. And jurisprudential innovation; which is what has been newly introduced and has no basis in Islamic law. This type is blameworthy and entirely misguidance.

What the Companions agreed upon, such as congregational Tarawih prayer, was called a linguistic innovation because it was introduced without a prior example, even though it is a Sunnah with a jurisprudential basis. From this, Imam Al-Shafi‘i's classification of innovation into praiseworthy and blameworthy is a classification of innovation in the linguistic sense. As for innovation in the jurisprudential sense, it is all blameworthy.