Tanween gives an “an, in, un” sound to the last letter of the Word that it comes upon. When Tanween comes in the shape of  double Kasra it reads “in”  as in (begin), when it comes in double fatha it reads “an” as in “can, man”, when it comes in double Damma shape it reads as  “oon” just like pronunciation of “moon” in Arabic form we would see the letter ‘m’ gets double Damma above and it reads in this manner.