More common spelling i think
I just checked a translation app that defined the word as fighting. Could the word mean the same thing as 시작 in a wrestling or boxing content?
It used as an encouraging
I don't think you can translat it properly
In martial arts the umpire says "Fight!"
No 시작 means start, (start fighting, start boxing, start a poomsae, start wherever...)
화이팅 in a word to encourage just like go, keep going ...