This app is a Zef Slang <-> Afrikaans Dictionary.
Zef is a South African term that can be likened to 'Kitch' or 'common'. Zef style has strong 1980s influences and is stereotypically associated South African caucasians of low-middle social-economic status. However, it not nesessarily a derogatory term. "It's like wearing high heels with a tracksuit. Being truly zef takes guts."(Urban Dictionary)
Note, The Zef Slang dictionary backend is from the website http://www.watkykjy.co.za .