The ripe fruit of Solanum burchellii, a berry, has brought the plant one of its Afrikaans common names, viz. lemoenbossie (little orange bush).
Spherical and orange fit as similarity features to the real, edible orange of the citrus family, but the spines, the long-lobed star-shape of the hairy calyx and particularly the hairs around the belly of the fruit in picture say otherwise. A fruit of S. burchellii becomes only about 1 cm in diameter when presenting its confident shine; definitely no orange!
The calyx behind the sphere has five long and narrow lobes, not holding on to the fruit in the photo with conviction. Those spines upon the branches and fruit stalk are said to become 1 cm long, here well shorter than the fruit is wide (Le Roux, et al, 2005; iNaturalist; http://solanaceaesource.org).