This is the 8120th most frequent Swedish word.
af
An archaic spelling of "av," meaning "of" or "by."
Here, "af" (modernly spelled "av") is used as a preposition indicating the cause.
Han blev rädd af den höga rösten.
He got scared by the loud voice.
In older Swedish, "af" could mean "off" or "away from," showing departure or separation.
Gå ej af vägen.
Do not get off the road.
Again, "af" (modernly spelled "av") is used as a preposition to denote authorship or origin.