Whose soul is sense meaning?
Similarly, you may ask, what does Sublunary lovers mean?
These "dull, sublunary lovers" (which literally means sub-lunary, or below the moon, or terrestrial—these lovers are earthly, whereas Donne and his wife know a heavenly sort of love) cannot allow a lover to leave because their love is entirely based around the other person's presence.
Subsequently, one may also ask, what does like gold to airy thinness beat mean?
Like gold to airy thinness beat. The poem is about how close their two souls are and the thinness of the gold is how brief/insubstantial the separation between them will be when he dies first.
The metaphors in line 6, though, keep us in nature, but move us to natural disasters: "tear-floods" and "sigh-tempests." These are hyperboles, or exaggerations, like "cry me a river." This hyphenated description is also commonly referred to as an epithet or a kenning.