These are special statues found all throughout the Island of Creation. They appear as a Sister of Fate (most likely Lahkesis), and it holds a green crystal/gem at the top. Kratos uses these statues to activate the Amulet of the Fates. When he is close enough range to one, the green crystal will give off a bright illumination, meaning that he can activate the amulet and slow down time temporarily.
At times, there are also other places and things that can serve the same purpose as these statues which help Kratos on his way. They usually include other scenery that contains the "crystal" that's also seen upon the Fates Statues.