Read this order
Book → Child: New knowledge, early study or information about a child. The emphasis is on something still being learned.
What changes in reverse?
Child → Book: A beginner learning something new, a child's education or a new project whose details are not yet known.
Child → Book ↗A practical example
A beginner opening a course book fits Child + Book. An unfamiliar concept introduced in a first lesson fits Book + Child. A literal child is possible, but not necessary when the question concerns a new skill.
Check it against your question
Keep the actual order and ask which part of the example fits your situation. An example illustrates a possible reading; it does not establish facts or promise an outcome.
The meanings behind the pair
Book: Book represents knowledge, study, privacy and secrets or information not yet disclosed. It may be a literal book, education or a matter that is still unknown.
Child: Child can represent an actual child, a new beginning or something small and inexperienced. The question determines whether the meaning is literal or describes an early stage.
These examples show possible ways to read the pair. Your question and the other cards may change the meaning.