What is the function of the POWER STEERING RACK & PINION on my accord and how do you know when it need to be replace?

the reason i ask is because yesterday i was under my car and notice the POWER STEERING RACK & PINION had some grease/oil coming out and i also notice some type of oil around the trasmission but it look like it is the same coming from the POWER STEERING RACK & PINION. thanks