LSB and USB are lower and upper sidebands. On the amateur radio bands it is a convention to use LSB below 10Mhz and USB above. You can find the bandplan for yo

LSB and USB are lower and upper sidebands. On the amateur radio bands it is a convention to use LSB below 10Mhz and USB above. You can find the bandplan for your country by duckduckgoing for 'bandplan usa' or wherever you live. If you want to learn it in a little more detail, and join in, take your basic amateur radio license. In the UK it is only a weekend course. I rarely operate, but taking the first two amateur licenses was one of the most interesting things I have ever done