What is the only true language a computer understands?

The only true language a computer understands is machine code. Machine code consists of binary instructions that the computer's processor can directly execute. This low-level language is composed of sequences of zeros and ones (binary), which correspond to specific operations and data that the hardware can process.

When software or programming code is written in high-level languages, bytecode, or assembly language, it must be translated into machine code for the computer's processor to execute the instructions. High-level code is more understandable for humans and needs to be compiled or interpreted to convert it into machine code. Similarly, bytecode is an intermediate representation used primarily in environments like the Java Virtual Machine, which also requires conversion to machine code. Assembly language, while closer to machine code and easier for humans to read than binary, still requires an assembler to convert it into machine code for execution.

Thus, machine code stands out as the fundamental language that the computer's hardware inherently understands and executes, making it the correct answer.