Hey hope this helps,

• Naming image files something descriptive is crucial to SEO and helps search engines understand what the image depicts

• HTML/CSS/JavaScript files don't directly affect SEO but do play a
  role in overall performance that in turn affects SEO.

• Folder names and structure often appear in the URL and should be a clean and descriptive, if content is logically organized into folders and subfolders it will help search engines understand the hierarchy and relationship between pages