What does 2 Corinthians 11:5 mean?

Second Corinthians has mostly been answering accusations from false apostles against Paul. We can guess at some of those accusations from the context of Paul's responses. They seem to have suggested that a true apostle, according to their warped approach, would not suffer so much or so often. They have also said that Paul is bold when writing from far away, but that in person "his bodily presence is weak, and his speech of no account" (2 Corinthians 10:10). The implication is that Paul is either a fraud, or a coward, or both.

By contrast, Paul suggests these false teachers think themselves "super apostles." They may have been highly skilled in the speaking and presentation skills so valued in Greek society. They may have been better- and stronger-looking than Paul. Culture of that era placed great value in entertaining, clever speech and showmanship. In short, the "super-apostles" were far more likely to be cast in the role of "apostle" in a play than Paul ever would have been.

In the end, though, only Paul was actually an apostle: a representative of Christ sent to bring the gospel to the Corinthians. These others were not. Paul declares here that he is not inferior to these "super-apostles" in any way. Paul does not mean to say they are actually "super-apostles." His use of that term is sarcastic: mocking their impressive-seeming external qualities.