This is called "Tanween" التنوين. (Nunation) It's an addition of a final nūn sound to a noun or adjective but you cant see written as "ن". there is 3 type of Tanween 1- ـً ‎ see symbol above the hyphen it's calld (تنوين بالفتح) sound like -an- at the end of the word. it's like "شكراً" 2- ـٌ above hyphen (تنوين بالضم) sound like -un- (رَجلٌ). 3- ـٍ under hyphen (تنوين بالكسر) sound like -in- at the end og the word (مَاضٍ).

شكرا is written without tashkeel and tanween only a native or who mastered arabic can read every word without tashkeel so basically , for me i see شكرا as شُكْراً the ً in the last of the word it's called tanween , it's a َ (fatha ) duplicated َ ...> ً ....> An ُ.....>ٌ.......>Un ِ .....>ٍ ......> In شكراً شكرٌ شكر

بسبب أنها أنتهت بتنوين الفتحة ف تلفظ كانها نُون مثل كتاباََ تقرأ هكذا كتابن و لكن في الكتابة تكتب هكذا كتابا و قِس هذا المثال على جميع كلمات تنوين الفتحة

In Arabic there are the so-called (movements) They control the character as you pronounce vowels in the English language So you'll learn (movements) ( َ ًٍ ِ )