in the scenario that JustGoDeep outlined (20,000 to 1) or moving from 20B shares to 1M shares of BIEL, you would simply take your current 50,500,000 / 20,000 = now you have 2525 shares but at $14 per share, or $35,350. This $35,350 should match +/- what you currently own.
This reverse split, if/when it happens will be done to move BIEL to a better stock trading board (NYSE) or similar. In practice it does not change your current holdings or dollar value on day one. Many people speculate it's the kiss of death for companies like BIEL...
I have personally never experienced a R/S, but I hope it happens for BIEL so we can get off the pennystock board and onto NYSE or NASDAQ.