The short version
For most South African homes, one ABC dry chemical powder (DCP) extinguisher of 2.5 to 4.5 kg near the kitchen exit, plus a fire blanket, covers the fires you're most likely to have. ABC means it works on burning solids (A), flammable liquids (B) and gas (C), and it's also safe on electrical fires.
Look for an extinguisher marked as meeting the relevant SANS standard, and have it serviced every year by a registered service company. Our fire extinguisher guide covers sizes, prices and how to use one, and extinguisher types explained covers the A, B, C, D, E and F classes.