Contango is when the price of the oil (or other commodities) some day in the future, in short often referred to as “futures”, is higher than the price of oil today. This offers market participants an incentive to buy oil today and store it for future use or sale.
Some participants buy oil contracts today, then turn around and sell them into the futures market. Using this approach makes it possible to pocket an almost no-risk profit. This also helps explain the 100 + Mb of oil and petroleum products presently stored on tankers waiting for deliveries.
In contango the price is lower in the future. I think you got it backwards. Normal backwardation is higher in the future than today’s spot price. That is why contango is unusual because it violates the normal risk/time trade off.