The statement is - False.
Felis concolor, or rather Puma concolor, and Felis domesticus, or rather Felis catus, can not mate with one another.
The cougar (Puma concolor) and the domestic cat (Felis catus), are both classified as small cats, or rather as Felis, and they are indeed relatively close related, but not close enough to be able to mate and produce offspring.
The reason for this is that the both species, over time, have evolved totally different traits, and while still sharing the same basic characteristics, there's some that are very different, which will not allow for the production of offspring.
One very big problem, apart from the genetic incompatibility, is the size difference. The domestic cat is pretty small, averaging 4-5 kg, while the cougar is the approximately same size as the big cats like the likes of the leopard and jaguar. A cougar fetus will be too big for a domestic cat to bear, while a domestic cat fetus will be too small for a cougar to bear.