Gees is the Afrikaans (South Africa) word for 'spirit' or 'motivation.' Pronounced using the rolling G sound common with many other South African words.
The most direct translation from the native Afrikaans (of South Africa) is "spirit" and that captures most, but not all of the essence of what gees is all about. An event or get together can have gees. A person can encapsulate gees.
Gees is also interchangeable with "cool", "fun", "positive" or "awesome" and is one of those fantastic words whose meaning shifts depending on context.