Machine language is the only language a computer is capable of understanding. The exact machine language for a program or action can differ by operating system. The specific operating system dictates how a compiler writes a program or action into machine language.

Low-level Programming Languages
A low-level programming language is a programming language that provides little or no abstraction from a computer’s instruction set architecture—commands or functions in the language map closely to processor instructions. Generally, this refers to either machine code or assembly language.
High-level Programming Languages
A high-level language (HLL) is a programming language such as C, FORTRAN, or Pascal that enables a programmer to write programs that are more or less independent of a particular type of computer. Such languages are considered high-level because they are closer to human languages and further from machine languages.