In America if you show someone only your middle finger you are telling someone F*** You. This is called a one finger salute, flipping someone off, giving them the bird etc. I heard in Finland they call it a hand unicorn.
Is this gesture also used to mean the same in other countries and if so what is it called that translates to English?
In France the middle finger is understood but more widely used is a fist pointing upward with the other hand in the bend of the elbow (canât seem to find an appropriate gif 
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Used the same as middle finger
I just tried what you described and believe that I have it correctâŠ
Is it like this 
Oh ok. I had my hand entirely into my elbow fold and not on my bicep. Your fine visual aid allowed me to correct this and I am now performing this gesture correctly as per French custom. Thanks as always.
If you ever think your message might not be fully getting across, adding a thrusting motion to whatever appendage you are holding out is also pretty widely understood across many cultures
Ironically I made mention that such aggressive gestures should be avoided in a paper I wrote about road rage that ended up getting publishedâŠ
That looks like my wife when I do not demonstrate proper listening skills or fail to put the toilet seat downâŠ
Lol!!!
In the Netherlands we use it too 
We use the Englisch translation for it, I do not think there is a Dutch word for it. Ore is there @Mno ?
This oneâs more accurate
Itâs one thatâs known here as well, although the finger is more popular these days. A quick search reveals the Greeks and Romans already used the middle finger. For example, you can Google Socrates and Aristophanes. I donât know any Dutch word for it @SoberWalker.
In Austria we also use the middle finger 
The gesture can be accompanied by swear words or unfriendly requests to do something. To give some examples: Arschloch, Oasch (asshole), schleich di, schöl di (slink off, fuck off), Wixer (wanker), fick di (go fuck yourself), leck mi (kiss my ass) ⊠We have lovely, creative swearwords like Nudlaug, FetznschÀdl, Gschissana, Funzn in all variations from deppert to eingspritzt, Pleampl, Sauwabn, and my personal favorite: The question: Leidest du an Hirnphimose? (Are you suffering from brain phimoses?) presented with a sardonic smile and raised eyebrows
The french âbras dâhonneurâ is an old school fuck you, my grand mother used to like it a lot 
Youngsters use the middle finger, which is more agressive I think
In the UK the middle finger means âup yoursâ the Vs (reversed victory sign) are used for fuck off, usually flicked up and down from the wrist at the object of your ire, hence the term flickering the Vs 
Awwwww, manâŠis that what that means? I thought it was someone showing me a bicep exercise.
Finland doesnât call it a hand unicorn, just me LOL.
Proper term would be keskisormi or keskari, for shot.
And itâs rude.
In Germany, if for some reason a person, in another vehicle was in the fast lane even temporarily, the FASTER vehicle driver would wag/ point his pointer finger to show you, you were wrong to be in the fast lane. Itâs crazy cause they can report you for hazardous driving to the polezei for being in the fast lane