The "bow", pronounced as in immitating a dog barking "bow-wow", is the front end of a ship.
The "stern" is the back end of a ship.
Hence, "from bow to stern" means from front to back, or, in your case, effectively "from head to toe".
Hope this helps
PS Please can you properly identify your origins/1st language. It helps people to help you, as they can identify the context of your postings.
Student or Learner