What does 1 kN per metre squared mean?

For every square metre (each side of the square is one metre long), there exists 1 kn.

An answer extension.Pressure is force per unit area 1 kilonewton per square meter is therefore a force one 1000 newtons per square meter.

1kN per square meter is also the definition of 1 kPa (one kilopascal). One pascal is simply 1N/m2.