There is no Labels in Outlook. But there are 2 solutions for managing emails: Folders and Categories.
Folders in Outlook will let you group emails for easier sorting:
On the File menu, point to New, and then click Folder.
In the Name box, enter a name for the folder.
In the Folder contains box, click the type of folder you want to create.
In the Select where to place the folder list, click the location for the folder.
Categories allow you to easily identify and group items. To assign a color category to a message from the message list, right-click the message. Select Categorize, then select a category from the list. You can rename the categories to something more meaningful to you or choose different colors for the categories.