If you have a Mac (mid-2013 or later) with macOS 10.13 or later, your Apple Watch can instantly unlock your Mac when it wakes from sleep. You need to be signed in to iCloud using the same Apple ID on both your Mac and Apple Watch.
Tip: To find the model year of your Mac, click the Apple menu in the top-left corner of your computer screen, then choose About This Mac. The year your Mac was made is listed next to the model—for example, “MacBook Pro (15-inch, 2018).”