What does Turbo Boost on a computer mean?

Answer 1

TurboBoost is an Intel feature that allows it to run the clock speed above its base clock speed when it detects there's additional load and provided that the thermal limits are satisfied (if it does hit the thermal limit, the processor will throttle [lower] its clock speed to cool itself down). Note that this does not equate to overclocking as the process of overclocking raises the limit of the TurboBoost clock.

Answer 2

In older PCs, there was a Turbo switch. The clones had a mode where they operated at roughly the same speed as the IBM PC. But for most tasks, users could select the faster speed.

In modern computers, there is the ability to overclock the processor in short bursts. That would allow it to give you an extra speed boost such as in competition games or heavy image rendering.