The Strait of Gibraltar separates the Iberian Peninsula and Africa. The two are separated only by 13 km (8.7 miles) at the narrowest point. We can easily see Africa from Spain as it is not that far away and that there are many highlands on both sides.
Flat-Earthers present the visibility of Africa from Spain as “evidence” Earth is flat. In reality, Africa is not that far from Spain. It is not far enough for the curvature of Earth to obstruct our view of Africa from Spain and vice versa.