What does "eres un buen cantante" mean?

My spanish teacher said this to me.. look at the ending on your verb. you need to make it agree with "yo" this is my sentence- sí yo estudiar español en la escuela how do i make it agree with "yo"

Which phrase describes bad dining etiquette? a. share food with others b. stay at the table until everyone finishes eating c. do not waste food. d. make noise while eating

Esta piña es mi piña. correct incorrect