I'm not terribly familiar with the WPPSI, so I won't be a lot of help, just a little. AE stands for "age equivalent" meaning that he is performing at the equivalent of an average child who is age 6 yrs 11 months, for example.
Based on those scores, the overall pattern to me would appear that he is quite strong in all areas and likely strongest in areas related to mathematical and spatial reasoning. Some lower scores (like the math fluency) really shouldn't be concerning. Uneven development is not uncommon in gifted children.
My oldest, who was tested on the WISC-IV and WJ-III at 7.5, had some scores on the WJ that were avg for age and some that were at 18+ AE. Her lower areas were often in subjects where she hadn't been exposed to any advanced material at that point and for which she just didn't have a natural proclivity to picking it up with no exposure. Even in math, which isn't her strongest area, she is testing very highly now b/c she has been accelerated in all areas including math.
Perhaps your son has very good abstract reasoning and number sense, but isn't quite as strong in whatever area is tested in math fluency. I don't know exactly what that subtest is testing.
