What does Tashkeel mean?
Covering harakat, tanween, shaddah, and sukoon together, tashkeel is what turns the bare rasm of the Quran into a text a reader can pronounce accurately without needing to already know it by memory.
Tajweed Rule
Tashkeel
تَشْكِيل · /taʃˈkiːl/
Tashkeel refers to the full set of diacritical marks added to Arabic script to guide correct vowel pronunciation.