It is not possible to establish the location of a foreign body without reference to at least 2 images.
On this image alone it is not possible to determine if this glass foreign body is located on the dorsal or plantar side of the foot.
Use of a second image shows the foreign body is within plantar-side soft tissues.
Note the radiographic marker which has been used to show the point of breach in the skin.
Dense material such as metal and glass show up easily with X-rays.
Other foreign bodies such as wood may not be dense enough to be visible - in which case use of ultrasound can help determine location.