I found this question as part of a set of questions. I'll just provide the answers of the set. It might help you with the other questions.
"The clock is underneath my desk?" - el reloj esta abajo de mi escritorio
"There is a door." - Hay una puerta.
"Its a table." - Es una mesa
"Where are the posters"? - Donde estan los letreros / Donde estan los carteles
How are "esta" and "estan" similar but different?
a. They are both third persons forms of the verb "estar", and one is singular and the other plural