There are a number of language courses on offer in South Africa.  The most commonly taught languages are English, Afrikaans and Zulu.  Certificate in English Language Training for Adults (CELTA) qualifies instructors to teach English to non-English speakers in South Johannesburg.

English language instruction is available at the Wits Language School in Johannesburg, which offers full-time English courses.

Estudiantes Embajadores de Mexico: Languages
EEM (Estudiantes Embajadores de Mexico) offers Spanish instruction for learners planning to spend an academic semester or year or in a Spanish-speaking country.

TEFL Certificate - Langahead School of Language
Langahead School of Language was started four years ago and offers the TEFL Certificate (approved by City & Guilds) as both part-time (3 times a year) and full-time: 2 Days Induction and 4 weeks of intensive training and teaching practice.

General English Courses in Johannesburg

International House Johannesburg (English, French, Portuguese, and Zulu language instruction)
http://www.ihjohannesburg.co.za/index.html

Listing of Afrikaans Tutors in Johannesburg
http://www.language-school-teachers.com/

English Language Schools in South Africa
http://www.learn4good.com/great_schools/schools_south_africa.htm

Language Schools in South Africa
http://www.saet.co.za/languageschools.aspx