I am guessing, but only because I know what FM stand for, (radio related)
Pulse Modulation
Frequency modulation
Mix.
Amplitude Modulation. ( that one with a bit of help from google)
Sync totally confuses me, sync what who were? lol
Not that my technical background helps me much, but that's a general issue I have in lmms. Although I do get some of the terms because of my technical background, it does not help me to understand what I am doing nor what that has to do with creating music.
AM vs FM does however remember of radio's, especially on what it does to the sound.
What in general has helped me though, using different synths. First time I opened synth 1,the triple ossicilator, and the mini moog, I was wtf?
Slowly I started to recognize knobs though, because all synths have most of them.
One day I hope to understand as much of the filters. Google is you're friend though, although you always find something lmms related, you can often find something that sheds some light on it.
https://en.wikipedia.org/wiki/Frequency_modulation
Because of this wiki, I think I am starting to understand a bit about the sync part.
I am very happy we have internet, this forum, and a lot of vids of people with DAW's and mixing.