This is the 892nd most frequent Serbian word.
својом
"Својом" means "with his/her/its/their own" in English.
"Својом" is used here to indicate possession, specifying that the friend belongs to Jovana in this context.
Јована је отишла у шетњу својом пријатељицом.
Jovana went for a walk with her friend.
"Својом" indicates possession here, referring back to the machine and thematically associating its speed.
Машина суши веш својом великом брзином.
The machine dries the laundry with its great speed.
"Својом" reflects possession, referring to the life experiences belonging to the writer, with gender agreement visible in the word ending.