Adaptive sync is the new image sync technology that is a better alternative to using Vsync.
There are two variants of adaptive sync.
One is by NVIDIA and they call it GSync and the other is by AMD and they call it Free sync.
In short unlike with Vsync which forces the graphics card to hold up and wait a minute so that the frames and the refresh rate of the monitor are synchronized (which also makes your frames sit exactly at that number of something like 60) which causes framerate latency which effects input lag, adaptive sync forces the monitor to change it's refresh rate to match whatever the GPU is spitting out (as long as frame rate is within a certain range, usually between 40fps and 144fps with a 144hz monitor) so that it removes screen tearing while not introducing the input lag that you get with V sync.
It used to be that NVIDIA graphics cards would only work with GSync but now they work with FreeSync too, but performance of it will vary from monitor to monitor when enabling GSync on a FreeSync monitor.
Just make sure you use a display port cable and not HDMI so that you can take advantage of the adaptive sync.