Office tools are a very important building block, because documents received for translation are in many cases provided as a document in Microsoft format (doc, docx, etc.). Microsoft Office (or compatible software) is therefore the tool most people would go for and you would need a version with at least the following: Word, Excel, PowerPoint.
However, this may be a bit expensive for the beginner, therefore I recommend
OpenOffice: It is fully compatible with Microsoft Office and sometimes even a bit better, and it’s free!
Why should I use Apache OpenOffice?
Apache OpenOffice is the leading open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more. It is available in many languages and works on all common computers. It stores all your data in an international open standard format and can also read and write files from other common office software packages. It can be downloaded and used completely free of charge for any purpose.
Available for: Windows, Mac OS X, Linux