You're right about the book, but wrong about the picture. P6 in this case is primary 6, for 10 year olds, approximately.
'xxx was how my P6 spelling book put it' refers to the definition of the word 'veteran'. How you 'put ' something is how you phrase it.
The picture that she 'saw' is the image in her own mind, conjured up by the word 'veteran' and the definition of a soldier returning to the war.