"SFX" stands for "Sound + Effects."
SFX's are onomatopoeia used in comics, such as manga and manwha. They attempt to give sound to 2D-drawn images by imitating real-life and imaginary sounds. These sounds are written in phoenetic alphabets - in Japanese manga, it's usually in Katakana and Hiragana.
What're SFX Translations?
After studying Japanese, as well as studying abroad in Japan for a semester, I decided to start practicing by reading manga in Japanese (with no English translations!).
Of course, this had its own problems. One of which was SFX's - it's not ordinary vocabulary, and without actually looking it up and translating them it's pretty much impossible to know what they really mean.
So, I tried googling for some SFX translations, and found that there wasn't actually any online resource for them. There were some translations here and there sure, in PDFs and image formats or in forums even. But just the idea of looking through that hubbub of data made me cringe. SOOOOO what do I do? I take the longest, logical-illogical route and make an online database full of them. Thus, it is now open to the public as SFX Translations.
I didn't just pull these translations out of my head - I had resources. If you know a definition or two for a SFX that isn't on this site, please leave a comment on the main page, or shoot me an email. This is a sort of open-source collaboration, so if you've got something you can share with everyone else, please do :).
If you have a website, or if you're part of a scanlation group etc, it would be awesome if you could help spread the word about SFX Translations :). I've made a link button you can use, but if you don't like it please feel free to make your own :P.