IMO it depends on the school as to what it really means. The only way to really know is to compare it with the other kids, (which might not go down well) and talk to teachers. (some of ours didn't understand the system themselves)
Youngest left yr6 with level 5?s English, maths and science, which that school (local CofE hijacked as feeder for independents) expected for the majority of it?s pupils (most had after school coaching) but most of the local junior school's turned out level 4?s and 3?s as standard.
Our local secondary said he?d now need to wait until yr 8 to do any new work as level 5?s weren?t expected for the majority until mid/end of yr 8, and yr7 was about ensuring everyone had made it to level 4. Those who'd already done so needed to make lots of posters, and wait. (there started many's bored misbehaviour btw)
However friends with children at the ?desirable? secondary, (we stood no chance for) had an intake of level 4?s to 5?s and where expected to be level 5 by the end of yr7, (and made fewer posters) but, the lot from his old school who mainly went to private schools expected to be equivalent of level 6 by then.
So loads depends on the school?s intake, expectations and if they?re streamed or mixed ability. (Mixed ability classes seem to move slower earlier, generally)
Additionally it depends if the subjects new to them, a child who?s never done French before yr7 gaining a level 3 is doing fine, but one who?s done it since yr3, isn?t doing so well.
I suspect the science is the wrong way round, and she?s expected to be able to progress two sub levels by then. They should be based on where she'll go from where she is now, not minimum requirements later.
(PS we headed in the opposite direction and are now H/E :))