South Africa's military is world class by African standards.They do have substantial maritime interests so subs make sense.
PS-South Africa has a very very competent arms industry with everything ranging from tank upgrades to SAMs to stand-off munitions.
Those subs will come with torpedoes for now,but could probably be outfitted with anti-ship missiles like the American Harpoon or the French Exocet.
Get ready for an episode of "Pimp My Sub"...
"They didn't get missiles with that thing, did they?"
Only one. And they can't load it without permission.