The increase means to add to and the sale means “when you buy it” we know this from that guy . He’s not wrong but truest the definition of sale is “the exchange of a commodity for money.” Meaning that sale is simply the item and what it’s sold for. If you take these two and put them together you get increase sale- the sale price being increased in the item.
Or simply a sale say for 40% being increased to 50% or anything above 40%. Hope that helped