An executable is a file containing instructions for a computer to run or “execute” some action. In other words, executable is simply another word for “program”.
Ultimately, all computer programs are nothing more than a series of simple instructions, stored in a file, and the computer’s CPU executes those instructions one after the other.
In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instructions", as opposed to a data file that must be interpreted (parsed) by a program to be meaningful.
The exact interpretation depends upon the use. "Instructions" is traditionally taken to mean machine code instructions for a physical CPU. In some contexts, a file containing scripting instructions (such as bytecode) may also be considered executable.