It's each person's measure of how much you go "hmm...! That was sooo good!" after eating 1 oz of a certain type of food.

In that example, 1 oz of beef contains 10 of my taste units while 1 oz of almonds contains 0.5 of my taste units.

Since each person's taste units are different, humans have decided that the best way to allocate food is to sell it on something called a "market", where each person can express their own individual taste units, or "preferences", by buying the food on this "market".

The price of the food on the market reflects the scarcity of the food and everything it took to produce it, although sometimes there are distortions which should be corrected externally (e.g. by a government), not by restricting the types of food we consume, but by addressing their root causes at the source (e.g. by taxing water consumption to address the tragedy of the commons, or by taxing CO2 production to address global warming). These taxes should be increased up to the point where consumption/pollution becomes sustainable.