Let's make it basics.

Let's say your code lives in ROM(Read Only Memory)

The CPU start reading from it at address 0x0.

It comes to the bus how many data at once can flow through it. And how many your cpu can read. Let's say the bus can transfer 8bit and your cpu can only read 8bit.

So. The first 8bits of 1s ans 0s goes to your cpu. The CPU then fetch the data, it decides it and then execut it. This is the instruction cycle.

And the CPU does it everytime. How often? It comes to the CPU clock speed. Let's say your cpu has 2.7Ghz. then it executes 2.7 billion instruction cycles a second.

But this goes muuuuch depper. It gets way complicated if you take an operating system into consideration.