Final answer:
An interpreter is a program that translates and executes instructions in a high-level language program, processing code line by line and combining translation and execution processes.
Step-by-step explanation:
The program that translates and executes the instructions in a high-level language program is called an interpreter. An interpreter reads the high-level program code and converts it into machine language, executing it line by line or statement by statement. Unlike a compiler, which translates the entire program before execution, an interpreter performs translation and execution simultaneously, which can be useful for debugging and allows for interactive programming. However, interpreted programs typically run slower than compiled ones due to this real-time translation.