It's a fancy calligraphy version of "Peace Be Upon Him" used specifically when referring to the prophet Muhammad. There are a handful similar phrases, mostly religious in nature. The most notable one would be ﷽ "In the name of Allah the merciful and compassionate" AKA the widest single codepoint in all of Unicode.
Since these are ligatures (though really complex ones) most software consider these as one "character" (try selecting part of the ligature; you can't).
