Variable replacement is a programming concept where the value of a variable is changed during the execution of a program. For example, if you have a variable called score that starts at 0, you can replace its value with 10 after a player earns points. This allows the program to keep track of changes and update information dynamically. In many programming languages, variable replacement is straightforward. You simply assign a new value to the variable using the assignment operator. For instance, writing score = 10 updates the score variable to reflect the new value, making it easy to manage and manipulate data throughout the program.