The outlet has a short-circuit in it. You need to contact an electrician immediately to prevent the possibility of a fire. Do not attempt to repair the outlet yourself.
Sparks should not be coming from any outlet. There is something in the outlet conducting electricity at an uncontrolled rate that is heating up and shooting off small fragments, sparks.
This means there is a short circuit between the wires in the outlet. This is an extreme fire and electrocution hazard. Shut off the power and contact an electrician.
