It means outside in swedish and is used when
people are coming from an specific place like inside and
outside.
It can also be an second name for someone named Fabian.
He is most of the time a person with a
micropenis and has big manboobs like he was a woman.
For example: Harry Potter kommer genom ytterdörren.
And translated to
english its gonna be: Harry Potter came through the front
door.
Another example: Hi, my name is
Fabian Ytter!