Really basic question is countdown -= Time.deltaTime; the same as countdown = countdown - Time.deltaTime; Im new to coding so i don’t know. Please help.

Yes it is. You can do the same with +=, *=, /= and so on.

Another handy shortcut operator for incrementing and decrementing is the ++ or – operator…

x++;

y–;

is the same as

x = x + 1, or x += 1

y = y - 1 or y–