There are 3 types of Tanween :
1) FATHATAIN 2) KASRATAIN 3) DHAMMATAIN
This lesson is about DHAMMATAIN
DHAMMATAIN symbol appears as two dammah symbols above a letter.
DHAMMATAIN sign consists of two components
(1) Dammah that produces 'U' sound
(2) Second Dammah is an unwritten letter Nun saakin, that produces 'N' sound.
Thus will produce 'UN' sound
(More lessons uploaded soon InshaAllah)