Documents like invoices, quotes etc. are composed automatically using templates.
A template is an RTF file which provides document layout (your company address and requisites, formatting, tables, headers and footers, company logo etc.) and placeholders which are filled with actual values when you apply the template during document creation.

Currently templates are provided in English only. 

You can, however, compose your own templates in other languages (by copying and translating the existing files or by creating new ones).

You can find the tamplates in "Business/Corporate Settings >> Templates".