In Swedish:

Lax = Salmon

Grava = preparing raw salmon (or other fish/meat) by keeping it in a mixture of salt, sugar and spices.

Salt and sugar keeps the fish from spoling, lactic acid bacteria preserves the fish. Back in the days this was done by digging a hole in the ground, cover the fish with spruce/fresh leaves and salt. Then lleaving it lying there for a couple of days. This also gives the origin of the word "grava" which in this context would bean "bury".