lock, stopper for a barrier (parking place ..... ?)

No, not for a barrier. But to lock something. What and how?

finger guillotine ! ;-)

I'm sure it can be that as well...

What size it has ?
..... may be a lock for a carabiner, backpack ......

Approximately 50-60 cm high construction. But not to lock either of those.

.... sh ..... - no. There is a wall , or street, in the background .....

Yes, this thing is on the street.

well I was going to say letter opener... buuuut that appears to be wrong after reading the comments.

This is to lock a power cord - box so no one else can use it!?!?

good guess hey... 100% off the rail but I thought you would like it!

No, not to lock power cords.

sculpture néolithique en métal forgé fabriqué en 972 avant JC

ils souriaient à cette époque !

Without instructions it may become something like that: Just a odd looking metal sculpture.

A tip. Where I found this, there were approximately a hundred similar metal things sticking out from the ground., solidly anchored on the street surface.

I got this.... move over all... it's to anchor a tree! yeah, what's my prize?

OR
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..
it's to lock a bike to?
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.
see I really have no clue!