With your substance.
With the first fruits of all your produce.
Then your barns will be filled with plenty of wheat.
Your vats will be bursting with wine.”
If you honor Yahweh with your goods, and especially the first fruits of your harvest, then your barns will be filled with wheat and other crops. Your vats will be bursting with wine. It seems that this was an agricultural society with wheat and grapes as the dominant crop.