I have a business trip in the Czech Republic and my visa has been approved with one entry only. I would like to ask if by any chance I can go out of the airport and explore Rome a little bit as I have an 8-hour layover on my way back to Manila from Prague. Since I only have 1 entry, does that mean that if my passport has been stamped with exit when leaving Prague, then I don't have a chance to go out in Rome even just for a layover?
For flights within the Schengen area, visas don't matter. You can fly between Rome and Prague a dozen times if you want, and exit the airport every time, as well as any other airport in the Schengen area. Only when you board the flight from Rome (or anywhere in Schengen) to outside Schengen area will your visa be used up as you exited.
The same is true on arrival: your visa is checked when you arrive at any airport inside Schengen - here Rome. From then on, you can fly around as you like.