"It is not my cup."
Translation:No es mi taza.
Because in Spanish you have to put the "no" before the verb it is negating. There are exceptions such as if the verb has an index/direct object pronoun before it the "no" come" before them.
I believe there's a significant difference. When you say "La taza no es mia" = "The cup is not mine" (Meaning simply that this particular cup does not belong to you. Hence, you don't imply that you even have your own cup). However, when you say "No es mi taza" = "It's not my cup", what you want to say is that you DO HAVE your own cup, but it is not the one you are speaking of. I hope this makes sense. It seems to me that it's a matter of emphasis.
Do you mean the Object of the posessive pronoun one is negating? "No it is not my cup".
No I was talking about sentences with object pronouns. I do not like coffee. No me gusta el café. Note how the object prounoun "me" is between the verb and the negation. That's just an exception. Otherwise the negation goes right before the verb.
You're better off sticking with él = he.
Usually when it is the subject, it is not expressed in Spanish. It is Monday = Es lunes. It is her pencil = Es su lápiz. It is not green = No es verde. It can't be = No puede ser.