al-Salafiyyah in essence is the methodology (manhaj) of following the Qurʾān and the Sunnah in beliefs, statements and actions, according to the understanding of the Righteous Predecessors (al-Salaf al-Ṣāliḥ), at the head of whom were the Companions of the Prophet ﷺ, and those who subsequently followed them in goodness; the Successors (Tābiʿūn) and those who came after them and followed them in goodness; the Followers of the Successors (Atbāʿ al-Tābiʿīn).
To learn more about al-Salafiyyah, please feel free to read the posts below:
Forty Ḥadīth On The Salafī Daʿwah