Possible meanings are 1) Moses speaks of the future as if it were the past to emphasize that what he is saying will come true, "Israel will dwell ... Jacob's spring will be secure" or 2) Moses is blessing Israel, "May Israel dwell ... and may Jacob's spring be secure." (See: [[rc://en/ta/man/translate/figs-pastforfuture]])
# Jacob's spring
Possible meanings are 1) Jacob's home or 2) Jacob's descendants. (See: [[rc://en/ta/man/translate/figs-metonymy]])
# let his heavens drop dew
The dew is spoken of as being so much that it is as if it were raining. Possible meanings are 1) Moses is blessing Israel, "may much dew cover the land like rain" or 2) Moses is telling what will happen in the future, "much dew will cover the land like rain." (See: [[rc://en/ta/man/translate/figs-metaphor]])