For official WCA scrambles hold the Square-1 with YELLOW on top and RED front. If your Square -1 has a different colourscheme, then make sure the front face middle layer has the small square on the left.
Notation is number, letters and letter character combinations to describe specific turns on a Square-1. The purpose of notation is to easily describe an algorithm or a scramble.
Important elements of Square-1 Notation:
The placement of the number within the brackets indicate whether you are turning the top or bottom layer.
Top Layer Turns:
The number (1 to 5) denotes how far to turn where and Edge = 1 unit and Corner = 2 units.
The SLASH character indicates a 180 degree turn of the Right hand side of the cube.