Refraction is a shift in the direction of waves as they pass from one medium to another. The image of the glow sticks appears to be misaligned or broken. The immersed part of the glow sticks emerge to be in a various location than the part of the glow sticks that widen above the water. That's because light rays from the immersed part of the glow sticks will converge in a various location than light rays from the part of the glowsticks that widen above the surface of the water. The bending of the path of light as it passes from the water to air causes the observed distortion of the image of the glow sticks.
