The full form of PBUH is Peace Be Upon Him. It’s used on Society & Culture ,Religion & Spirituality in Worldwide

Peace be upon him (عَلَيْهِ ٱلسَّلَامُ ʿalayhi s-salām), is an Arabic phrase of veneration or durood attached to the names of holy figures in Islam. The English phrase is also given the abbreviation PBUH in English-language writing. An extended variant of the phrase reads ṣallā -llāhu ʿalayhī wa-ʾālihī wa-sallam^a (Arabic: صَلَّى ٱللَّٰهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ‎, lit. ‘God bless him and his family and grant him peace’) and it is often abbreviated SAW or SAWS in writing. The Arabic phrase is given the name Salawat. The phrase is encoded as a ligature at Unicode code point U+FDFA ﷺ ARABIC LIGATURE SALLALLAHOU ALAYHE WASALLAM

Some Islamic scholars have voiced disagreement with the practice of abbreviating these phrases, arguing that it demonstrates laziness and a lack of respect