Watch how to Insert Google Drive Folder, Docs, Sheets, Slides, and Forms into a Google Site:
You can embed Google documents, spreadsheets, presentations, and forms into your Google Site in two simple steps:
Click the Edit page icon, which looks like a pencil icon, to open the page editor.
Place the cursor where you'd like to insert the object.
From the Insert menu, select the object you'd like to insert.
Note: The inserted object will be view-only to the public. However, when the contents of the objects are updated at its source and published, it is updated automatically within your site.
Anyone with collaborator access to your site will be able to view a link under each embedded object that will allow them to pop out an editable version of the object.