Okay kiddo, so have you ever heard of a magic trick where a person can change their voice to sound like someone else? Well, that's kind of what fmllr does.
You see, when someone talks, their voice has a unique sound that is made up of different frequencies. Fmllr is a computer program that can listen to someone's voice and figure out how to change it to sound more like someone else's voice.
To do this, fmllr uses a lot of math and fancy algorithms (big complicated rules that the computer follows). It listens to someone's voice and looks for patterns in the different frequencies that make up the sound. Then, it uses these patterns to adjust how the voice sounds in different ways.
For example, if someone wants to sound like a man with a deep voice, fmllr might adjust their voice by making their lower frequencies louder and their higher frequencies softer.
It's kind of like playing with the knobs on a stereo to make the music sound different. With fmllr, instead of adjusting the bass and treble knobs, it adjusts the different frequencies in someone's voice to give them a different sound.
So that's the magic of fmllr, it can change someone's voice to sound like someone else's voice. But unlike a magic trick, fmllr uses a lot of math and fancy algorithms to do it!