Algorithmic efficiency is like a race. Suppose there are two people, Jane and Matt, who each want to run one mile. Even though they both want to do the same thing, they will likely use different strategies to do it. Jane might decide to jog the whole mile, while Matt might run it and stop and walk for short breaks in between.
Jane is said to be more efficient because she was able to get to the finish line faster than Matt. In mathematics, algorithmic efficiency is like a race, but instead of two people racing, it is two different strategies used to solve a problem. Using the same example, if Jane and Matt both had to get to the finish line, Jane's strategy of jogging is more efficient because she will get to the finish line faster than Matt.