Google Sheets -> [docs|pdfs|webpages|email]

I've come across multiple people wanting to inject a template (HTML, PDF, DOCX) with a spreadsheet's row's values.

For examples:

e-com store with the product names and descriptions in g-docs and wanting to create static-webpages for each product).

I want to write a pdf letter to all employees with their name and employee id and job title using a template.

Questions:

1. How do you describe such a service? (notice how the title is not great).
2. How would you build this or use a service that does this?