This non inspirational book has been written by some counsellor type person who holds Christian views (e.g. complement your wife for the way she spoke to the old lady at church). I get the impression has written several similar books. Suggest everyone has a predominate language of love, the five languages are:
Words of affirmation
Acts of service
Seemingly learning what your partners preferred language allows you to communicate better. Amusingly I couldn’t quite work out which was my preferred language!