Microsoft Office online is simply a cut down version of the full office suite. It’s fine for basic tasks and files are automatically stored in your Onedrive online. It’s a free way of getting Microsoft’s flagship tools and all you need is a Microsoft account – info about Microsoft accounts here
Just like Microsoft Google has it’s own on line office. It works in much the same way, you sign in and simply click to create a new document or sheet or slide. Sheets and slides are Googles name for spreadsheets and presentations, docs are saved in Google’s own format but any created document or sheet etc can be shared or downloaded in Microsoft’s format.
Not many have heard of this but Ashampoo has been producing good software for years and their office software is very good. It’s not free but it is good value for money and you can download a trial. There is a free version also from Softmaker who sell their own version. The Free version (Ad supported) is here (Free email registration req’d)