There are some extension that i use normally but the most of developers may bot be using it so mentioned that here also to make things clear.
There many other extension that can be very useful depending on your workflow and your uses and it's not in listed here. You can always install them. if don't like to use one of this extension that comes with extension pack then you can disable it or maybe uninstall that particular extension.
Here is list of extensions included in this extension-pack with small description.
Supercharge the Git capabilities built into Visual Studio Code — Visualize code authorship at a glance via Git blame annotations and code lens, seamlessly navigate and explore Git repositories, gain valuable insights via powerful comparison commands, and so much more Gitlens.
It helps you to easily access your projects, no matter where they are located. Don't miss that important projects anymore. You can define your own Favorite projects, or choose for auto-detect VSCode projects, Git, Mercurial and SVN repositories or any folder.