What is the meaning of Pp?

pianissimo

per procurationem - Latin for by agency or by proxy - used on a letter to indicate that has been signed on somebody else's behalf.

Initialism of percentage point.

Initialism of past participle.

proton and proton (used attributively to describe a collision or other interaction of these two particles)

Eye dialect spelling of pee-pee.

Initialism of per person.

Abbreviation of pages (plural of p).

initialism of photo de profil (“profile picture”)

abbreviation of perempuan (“female, woman”)

initialism of ponto percentual or ponto de percentagem.

Source: wiktionary.org