The first value (2.5 on the first line) is a rough grade equivalency estimate for your child's skills.
The second value ("PRI", 98/90 on the first line) is a relative proficiency index, where the first of the two numbers shows your child's percentage of mastery when others of the same age would be expected to show 90% mastery. Note that this is not a percentile. Note also that the second number's always 90 for this one. So, for example, your child shows 98% mastery of math reasoning when others his age show 90% mastery.
The last value on each line is the scaled score.
He's obviously on the bright side. Note that his math reasoning is not his strongest area here, but he does show some good academic advancement, along with good processing types of skills. I think it's impossible to tell whether he's gifted from a WJ subset given hurriedly by someone who may or may not be an expert on testing gifted kids, but he may well be gifted.