Why square graph paper distorts knitting charts
At a gauge of 20 stitches and 28 rows per 4 inches, one stitch is 4 ÷ 20 = 0.20 inch wide but only 4 ÷ 28 ≈ 0.14 inch tall. Chart a design on square paper and every row comes out 0.20 ÷ 0.14 = 1.4 times shorter than you drew it: a circle knits up as a flattened oval, a heart as a squat one, letters look stretched sideways.
Knitter's graph paper fixes this by drawing each cell at the true proportions of a stitch. Enter your swatch gauge (stitches and rows over 4 inches or 10 cm, which knitters treat as the same) and the cells come out exactly that shape and size, so the chart is also a full-size preview.
Reading the chart
Bold lines fall every 10 stitches and 10 rows. Rows are numbered up the right edge and stitches along the bottom from the right, the way charts for flat knitting are read: right-side rows right to left, starting at the bottom.