- roll out - 公開するとかお披露目するとか。
Microsoft released to those in the "Fast Ring" Build 10049, the first with Spartan, on March 30. Today's Windows 10 Desktop preview is the second Microsoft has made available to testers in March, and the fourth Windows 10 Desktop build the company has released as of October 1, 2014.
Like Windows 10 Desktop -- which runs on PCs, laptops and tablets -- Spartan is still not feature-complete at this point. The first Spartan preview does, however, include most of the functionality that Microsoft execs showed off on January 21 during an early demo of Spartan as part of a Windows 10 press event.
- execs - 幹部。「実行」とか関係ないですよ。
- show off - 見せびらかす。やな感じの言葉ですが、そういう意味合いが含まれるのかどうか不明。ここでは、単に「披露した」的な意味かもしれない。