That seems like way too high of a bar for the word knows. Someone who plays the guitar for 3 years certainly knows the guitar, even if they're not great at it. Who would you say knows Africa? Someone who lives all their life in Kongo? They might know Kongo, but probably know less about the varied experiences of Africa as a continent than someone who spends 3 years traveling around the whole of Africa.

If he travelled that much, then yeah. It’s just a phrase.