The instructions to this basic granny square are spelled out plainly for those just starting out with granny squares.
The gauge would be 4 rounds= 4” X 4” swatch.
Typically a G or H hook will achieve this gauge using a medium weight 4 ply like Caron’s Simply soft is nice, but really any medium weight yarn will work.
It takes only a few yards of yarn. It’s great for using up leftover yarn.
The blocks can be sewn or slip stitched together to make afghans and even clothing.