I think you'll find that BSA refers to bon de souscription d'action. At sources like the GDT this is translated in the above form.

Stock warrants are a form of option. providing the holder with the right to buy a stock. Very often, when the holder "exercises" this right, the company has to issue new equity. As a result there are more shares in circulation and the earnings are diluted, since in the earnings per share equation (earnings/number of shares) the same figure is in the numerator (earnings) but the denominator (the number of shares in circulation) has increased, i.e. the return to which the share entitles the holder shall, ceteris paribus, decrease.