Microsoft announced new icons for its Office suite all the way back at the end of 2018, but the rollout of those new icons hasn't been exactly quick. Today, however, Microsoft announced build 11514.20004 of the Office apps which is being rolled out to Office Insider Fast users on Windows, and it sees the four most prominent apps in the suite getting new icons.
Specifically, we're talking about Word, PowerPoint, Excel, and Outlook, all of which now have the product icons revealed last year. The new Outlook icon was made available for the iOS app earlier this week, too. You may see a couple of issues with this, though. Pinned tiles for the apps may not update with these icons, plus associated file types won't display the new icons either. Only the product icons themselves have been updated, with a broader rollout coming soon.
As for new features, Word now supports basic co-authoring of documents that contain macros, whereas you would previously be locked out of a document if someone else is editing it. Basic co-authoring means AutoSave and real-time typing won't be available, and you also can't edit the VBA macros in co-authoring mode.
In addition to the new features and changes, the new builds come with a range of bug fixes for a lot of the Office apps. These include an issue where Word would constantly display a "Checking for changes" message, Access creating an extra shortcut, and more. You can see the full list of changes here.
The new build should show up for you automatically, but you can try checking manually for updates if you haven't received it yet.