Let's start with the basics.
The Layout - Each move in a Square-1 algorithm is wrapped inside 2 brackets like this (1,0). The number before the comma means we are turning the top layer, the number after the comma means we are turning the bottom layer. Example: (1,0) (3,2) (-1,0)
The Number - The number denotes how many times you move that layer in 30° increments.
1 = 30°
2 = 60°
3 = 90°
4 = 120°
You might be asking yourself, how do i know how many degrees° im turning that layer? Do i need to buy a protractor😅
If looking at a solved Square-1, the little edge pieces on the top and bottom layer are 30° whilst the bigger corner pieces are 60°. From this information we know that a (2,0) would mean we have to turn the top layer 1 big piece (or 2 little pieces).
The Negative (-1,-1) - Okay, just like a normal cube, we have clockwise and anti-clockwise rotations. The way these are shown in a Square-1 algorithm are by negative numbers. As you can probably tell, a positive number means a clockwise rotation whilst a negative number is an anti-clockwise (counter-clockwise) rotation. Example: (-1,-3) we would turn the top layer 1 30° segment anti-clockwise and also turn the bottom layer 90° anti-clockwise.
The Slice / - Outside of the bracket moves you will have to slice the puzzle. A slice is just a 180° rotation of the right hand layer (as shown in the photo below). A typical algorithm will look like this / (3,-3) / (3,0) / (-3,0) / (0,3) / (-3,0) / Every time we see a / we just slice that right layer 180° and proceed to do the moves inside the brackets that follow it. Really simple.