The person who is "one call away" is saying that they are very near, and readily available to the caller. Not only is the person suggesting they are very near, but that they are capable of doing great things, comparing themselves to Superman (which is definitely a hyperbole). As for using the saying, "got nothing on me," It's not something we would use often, but is still commonly understood to mean that "I'm just as good at them," or "they are not any better than me at such and such." Hope that helps, Merrit

One call away means that, if you have a problem you can call that person and they will stop whatever they are doing so that they can help you. Superman got nothing on me means that, whatever skills Superman has, I am better than him. Here in England, "got nothing on" is perhaps only used in a humorous setting.

One call away? What doES it mean?

Tonatiuh, your explanation is very clear especially the example that you give make a lot of sense, thank you very much!

Sorry the way I phrased this it makes it sound like "Superman got nothing on me" is common phrase but it's really just "got nothing on me"