If you are trying to add a Managed Metadata type column and getting “The Taxonomy feature (Feature ID “73EF14B1-13A9-416b-A9B5-ECECA2B0604C”) has not been activated” error then here is the quickest way to enable the required feature by using following PowerShell cmdlet:
Enable-SPFeature -id “73EF14B1-13A9-416b-A9B5-ECECA2B0604C” -url “YourSiteUrl”