'Salt' symbolizes the desire of truth and good to be conjoined with each other. So, a salt can conjoin water, which corresponds to truth, with oil, which corresponds to good.

Salt can also have a negative meaning. 'Lot's wife becoming a statue of salt' signifies all the good of truth being vastated, or laid waste, in the church that Lot represented. In that story, Lot's wife represented a form of 'truth' that turned itself away from 'good,' and looked instead to doctrinal matters. Because 'salt' can signify vastation, and 'cities' signify doctrinal aspects of truth, in old times they sowed cities with salt when they were destroyed to prevent them from being rebuilt, as in Judges 9:45

(Referencat: Arcana Coelestia 10300)

2003. 'As for Me, behold, My covenant is with you' means union of the Divine Essence with the Human Essence. This is clear from the meaning of 'a covenant' as conjunction, dealt with in 665, 666, 1023, 1038. Here it is the union of the Divine Essence with the Human Essence, as is evident from this meaning and from the internal sense of what has gone before, and so from the actual words 'My covenant is with you'.