Stock is a share in an ownership of a company.
This means that you have a claim to the company’s assets and earnings.
The more stock you have, the more share you hold in a company. Just for your interest and to avoid confusion, equity, shares and stocks means the same.
CFD trading = Profit from Short Selling
In case you trade Stocks in a form of CFD, you can “short sell” to profit from falling prices.
In this case, the interest/dividend will be negative, because you are doing the contrary of “having a claim to the company’s assets and earnings”.