Types C, M and N, 230 V, 50 Hz – those are the basics for electricity in Eswatini. At 230 V the supply matches what UK and European appliances expect, so no converter is needed.
The same socket system is used in Namibia and South Africa, so one adapter covers all of them. Watch out when moving on: Zambia, Malawi and Ghana use a completely different system. 3 of the 55 destinations in Africa share the plug types of Eswatini.
Protective earth
Grounded and ungrounded sockets may occur
Not every socket in Eswatini is earthed: Types M and N yes, Type C no. Class I appliances belong in an earthed outlet.