It means the overall operating speed of your CPU. However, if you see the phrase 'clock speed' in any of the product specifications above, it means a base clock speed. Otherwise, product specifications include other wordings, such as boost clock up to. So, please don't confuse it with the base clock speed. Let's understand it with an example of a quad-core CPU. If the CPU specification says it has 3 GHz of base clock speed, then it indicates that all four cores will reach 3 GHz under load, provided that the chip is cool. If you want to go beyond the given base clock speed, you must go for a processor with an overclock or boost clock feature.