Definition:

Adjective (describing something): Used to express that something is cool, awesome, or impressive. 
Example: “Hy is ‘n duid’like brah.” (That guy is awesome.)

Interjection / reply: Used as a casual response to mean “okay,” “alright,” or “got it.” 
Example: “Os ontmoet so 5 uur se kant.” – “Duid’lik.” (We’ll meet at 5-ish. – Okay.)