Shaddah, our happy tale bear buddy, it makes a shaddah combination in which it attaches previous letter with the next letter of word.
The direction of movement will depend on the harkah seen on it.
The shaddah means two same letters together.
Out of these 2,
first letter is with sukoon and second letter with the showed direction of movement (haraka) on it,
It can be any one out of dammah, kasrah and fathah.
Short vowels in Arabic are basic signs over letters.
These harakat are giving life to these letters, as the movement it gives to letter is sign of life.
Formula of Word = letters + their harakat