Horned Adder or Horned Puff Adder or Horned Viper * Horingadder * Bitis Caudalis

It is a venomous viper species. It is easily distinguished by the presence of a single, large horn-like scale over each eye.
By Chantelle Bosch - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=53474880
Snake Slang
A short, stout little viper, it usually averages 30–40 cm (12–15.5 in) in total length (body + tail). The largest specimen reported being seen is a female from southern Botswana measuring 51.5 cm.

The snake is found in far arid regions of southwest Africa: southwest Angola, Namibia, across the Kalahari Desert of southern Botswana.

The Horned Adder venom is mildly Cytotoxic. This can cause a lot of pain and swelling. In severe cases it can cause shock and necrosis around the area of the bite.

Sources:
(*) https://en.wikipedia.org/wiki/Horned_adder
(*) https://www.africansnakebiteinstitute.com/snake/horned-adder/
(*) https://www.reptilerange.com/horned-adder-information/