I kind of understand what's the use of BGP, but the article was lacking too many details even for me. cloudflare has a better article, their conclusion is that this was probably an accident and not an attack, because the leaked routes were so low priority that it couldn't cayse traffic to be rerouted.
they didn't say but I think perhaps what it could have done is overload the venezuelan state ISP with traffic they shouldn't handle, but I don't know for sure

https://blog.cloudflare.com/bgp-route-leak-venezuela/