Is sentence correct?

It is correct.

To know what it means exactly, some knowledge of the context is necessary.

For example, if the book was for Mary's sister/friend, Mary could suggest to James which book might be suitable.

Or, she could have simply given him some money if he didn't have enough cash with him. There could be various meanings.

I thought that when you helped somebody do something, you should also join in. For example, if someone asks me "Help me carry this table", he should carrying the table together with me.

Is helped used above different from the sentence I posted.

Many thanks.

It is the same meaning, but it does not mean only physical help, as in helping to carry something.

You can also help someone by simply making a suggestion.

For example, if you are in a foreign city and needing directions, you might say to someone "Can you help me please?....."

Thanks.