This quote is referring to the success of the Wu-Tang Clan, a hip-hop group from the late 1980s and early 1990s. In the quote, the speaker is acknowledging that their success is special and unique, noting that it is unlike anything else out there. The speaker is recognizing that their success was something incredibly special, and they likely won’t ever see that kind of success in another hip-hop group, like a new Jackson Five. He recognizes that some groups only come along once, and the Wu-Tang Clan was that group.