When you are or considered emo. You are very emotional. Signs of people being emo is liking the colour black; cutting yourself on your wrist or other parts of your body and letting it bleed; say very emotional things and be very gloomy. But sometimes people like to listen to emo music. Music sung by emo singers or bands. The songs usually have a very emotional meaning of somewhat and the singer usually sings in a weird way eg screaamm their head off one second and sing like a lullaby the second but this may also be considered punk too.
Goths are a type of emo. But kinda in a different way. Emo can be considered a type of fashion; wearing black and dying their hair black, wearing mascara and paint their fingernails black and ect...
That's like from what i know. If my chinese was very advanced i would've translated this into chinese but I'm not and never will or if i try, no-one will understand so I only can explain this in english.