What does Salafim mean?
Salafism is a group of Islam who strive to follow and adhere to the ways and teachings of the Salaf Saliheen (pious predecessors of Islam). Salaf means predecessor or ancestor. That could be anyone who has passed. Saliheen means pious.
The Salaf Saliheen are the Muslim scholars of the first three generations of Islam. These are the Companions of the Prophet (ﷺ), the Tabi'in (students of the Companions) and the Atba Tabi'in (followers of the Tabi'in).
Salafism is actually not a separate sect in Islam like the Khawarij, Shism or Murjia are. It is a name that has recently been made up to distinguish itself from other sects. Salafism is actually Sunnism, but with a different name.
Several people claim to be Sunni. It is then difficult for a true Sunni to distinguish himself. So that is done, among other things, with the term Salafi.