It is useful because one fixed bitrate is rarely ideal for every connection, device and viewing moment.
How the idea works
The same content can be prepared in multiple representations. During playback, the player may select among those representations according to its logic and observed conditions.
What ABR can help with
It can help balance visual quality against buffering risk when bandwidth or device conditions vary.
Implementation is system-specific
Protocols, rendition ladders, codecs and player algorithms matter. This educational page does not claim a specific Galxy ABR feature set until those implementation details are confirmed.
Next step
If you are evaluating a platform rather than learning the concept, compare the operational workflow and the cost model together.