Lets say you have shares owed to you by X,but you will not get them for a few days okay.So in turn you sell those shares short on the market.Few days goes by and x pays you the shares owed too you okay.
You have just sold short shares and covered when x gave you the shares.
Same thing applies with these Scammers
"these posts are not of a licensed investment advisor or analyst nor does he give out buy, sell or hold advice to anyone"