Convergence is when evolutionists say that something evolved more than once independently. Evolutionists try to make it sound like an exciting thing, but really, it is a problem for their framework.
For example, the octopus has an eye that is remarkably like a human’s, but because octopi and humans are not closely related according to evolutionists, they must say that these striking similarities evolved independently. It’s very difficult for them to make this sound convincing. A much better explanation is that God created nature to look unlike evolution, and so He placed things like that in nature as “stop signs” to evolutionists.