Chip away any cracked edges of the hole before patching it. Use a small sledgehammer and cold chisel to break away the cement along the cracked edges.
Clean out the hole using a wire brush. It is important to remove any loose cement or other debris from the hole so that the patch will adhere properly.
Prepare a batch of cement-patching compound in a small bucket. Follow the manufacturer's instructions.
Use a putty knife to scoop out a generous amount of the patching compound onto a small board or straight-edge taping knife. Hold the taping knife or board with the patching compound at the base of the hole.
Force the patching compound into the hole using a putty knife. Fill the hole completely with the patching compound until the compound is overflowing from the hole a bit.
Smooth out the patch using a pointing trowel. Use the edge of the trowel to go back and forth over the hole to smooth out the patching compound. If the hole is really large, use a large trowel to smooth out the patch.
Allow the patching compound to dry and cure according to the manufacturer’s instructions.