What do you call this in English?
The safety pin is a variation of the regular pin which includes a simple spring mechanism and a clasp. The clasp serves two purposes: to form a closed loop thereby properly fastening the pin to whatever it is applied to, and to cover the end of the pin to protect the user from the sharp point.
I believe you can call this a pin when it is clear from context that the item is a safety pin. Otherwise, a pin can refer to a variety of fastening devices, not to mention other devices unrelated to fastening.