What does it mean for a kid if wbc and rbc count is normal while differential is not ( neutrophils low, monocytes a bit high, eosinophils high ) ?

Blood count: Elevated eosinophils may indicate an allergic condition or infection from a parasite

Depends: Could be just an infection that has shifted the differential, but if the changes should persist, they may need further evaluation.

Maybe normal: The fact that the WBC and RBC are normal is very reassuring. A slightly elevated monocyte count can be related to a viral infection most likely although it may be raised with other types of infection. Eosinophils may be elevated due to allergy/allergic reaction most likely although it may be seen in parasitic infections also. You need to take into account why blood test was done and pt symptoms