The Key Stage Standards page allows you to see the highest Pre Key Stage Standard that a pupil is assessed against, for the core subjects of Reading, Writing and Maths. This assessment could be against any level of the depth of learning: shallow, emerging, developing, deepening or functional.
In the example above, Matthew has data against a PK3 standard in Reading, PK5 in Writing and PK4 in Maths. This suggests the PK standard level Matthew is working at.