what does idhgaam noon sakeen means?
Idghaam means merging. So when a letter has "idghaam" into another, it merges into second letter so that what is heard is the second letter, empahisized with a shaddah (double). Noon is the Arabic letter
. Saakinah (you wrote sakeen, but the correct word is saakinah) means voweless. So idghaam noon saakinah means, the merging of the non-voweled letter
into the letter which follows it.
For more information please see: