A full Google Doc can be translated at once.
Note: If your document is in Microsoft Word, you can right-click on the file icon and select 'Open With...' from the menu and then select Google Doc to open it as a Doc. Similarly, if your document is a PDF, you can right-click on the file icon and select 'Open With..." from the menu and then select Microsoft Word to open it as a Word doc. You can save that Word doc and open it as a Google Doc but each translation can lose some formatting and text. There are Add-ons in the Google Play Store to open PDFs directly in a Google Doc.
Step 1
Select Translate from the Tools menu
A. Open your document in Google Doc and select Tools from the top menu.
B. Select 'Translate document from the menu
Step 2
Chose a language.
A. This process does not replace your old Doc, it creates a new Doc and so needs a new name. You can accept the name that is generated automatically or rename it as you want. enter a name for the translated document.
B. Select the language you want to translate into from 140 languages listed in the dropdown menu.
C. Select the 'Translate' button.
The translated document will open in a new window and will also be available in Google Drive. The original document will remain unchanged.
The translation is generally good enough to get the message across, but it's not perfect. If you need an accurate translation, you can have a fluent or native speaker look at the document.
Please note that words that are pasted in as a picture will not translate. To change those a replacement picture will need to be created.