What does "Sow in 30cm squares, spacing four seeds every 7.5cm, 15mm deep mean

[Wills]

I'm not good spatially - can get rows but why squares?

Sometimes things pollinate better in squares. Sweetcorn is better sown in blocks because it is wind pollinated. What is it?

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Like that, but more even so it's a square not a rectangle. each seed 7.5cm away from its neighbour in the column or row.

cheers

Carrots by the way