good grades for conference = buenas notas para la conferencia
It means: "What do you have to do in order to get good grades?"
Buenos grados
Me saco buenas calificaciones.
Soy bueno
Bastante bien.
Good-bye is adíos.
it means "how are you when you get a good grade"
Siempre obtengo buenas calificaciones/notas
"Good" in Spanish is "bueno" or "buena" (depending on whether the noun being modified by the adjective "good" is masculine or feminine).
no es bueno para mi
No he does not get good grades he gets bad grades!
Presumably it means that you'll get good grades in Spanish class, and that if you ever have to go to Spain you'll be able to understand the directions to the bathroom. Other than that, it doesn't really "mean" anything.