Say you've got a working copy of your code and want to label it so that you can retrieve that version at any time. You could also use versioning to accomplish this but you may not want to cut a version for a valid reason (eg. your code is not going to prod anytime soon but you still want to stamp it at a known/working state).
Step-by-step guide
In Visual Studio, within Source Control Explorer, navigate to your project, right-click on it, select Advanced, and then Apply Label...
Then name your Label and give it a descriptive comment so that it's clear why/when you created the Label.
To find your Label, again right-click on your project, select Find, and then Find Label...
Use the dialog to search for your Label
If you double-click on the search result that matches your Label, it will open the Label view which allows you to do various things including retrieving the code with that Label
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