# For the people sow the wind and reap the whirlwind

To sow or plant the wind is to act in useless or destructive ways. To reap the whirlwind is to suffer disaster from one's own actions.

# The standing grain has no heads

Here "head" refers to the part of the plant where the grain is. A stalk with no head has nothing to give to the farmer. In the same way, Israel's actions will result in nothing good. 

# If it does come to maturity, foreigners will devour it

If any of Israel's actions do happen to result in something good, Israel's enemies will come and take it from them.