Dogs bury things that they see as valuable in order to save them for later. By burying socks, your dog thinks they are a special thing to save for later!
To stop the behavior, the easy answer is to make sure socks are put away.
If that can’t happen, rotate your dog’s toys. If their toys are exciting and entertaining then there is no need to horde socks. Likewise, you can also buy toys that are similar to the sock fabric.
Sometimes we teach dogs that the sock is a valuable thing because anytime they have it, we chase them and take it back. If you see them with the sock, calmly ask them to sit or trade it for a toy. When your dog complies, praise them lavishly!
Another hint is to increase activity level and utilize interactive toys (treat ball/muffin tin/puzzles). If your dog is tired and has other fun things to play with, then there will be no time for sock burying.