That's a good guess but it's not quite correct. When the processor is running, it stores information (both data and instructions) in internal storage places called "registers". What the 64-bit means is that these registers hold numbers that are 64 bits in length. Remember binary? It's the way a computer represents numbers. As an example, a binary number that measures 8 bits can go from 0 to 255. So an 8-bit processor has registers that can only "understand" numbers from 0 to 255.. quite limited, don't you think?
Now, a 64-bit binary number goes from 0 to 18,446,744,073,709,551,616!! It means it can recognize a virtually infinite amount of numbers. This represents a huge increase over 32-bit computing, specially in the amount of RAM the processor can address.
So the short answer to your question is nope, it doesn't mean the processor can "calculate" 64 bits of information, it's just a statement of the format the processor uses to store internal information.
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