They mean "fewer people willing to cross the bid-ask spread to buy a stock than the number of people willing to cross the bid-ask spread to sell a stock"; what

They mean "fewer people willing to cross the bid-ask spread to buy a stock than the number of people willing to cross the bid-ask spread to sell a stock"; what matters is who is crossing the line? if it's the buyer side of the transaction, price trends up. If the seller is accepting a small % loss on the sale, the price trends down.