Hello Ren !
The translation depends on the context, because two verbs in Spanish can be translated as "was" in past time.
The verb "SER" ( to be ) and the verb "ESTAR". In English, the verb "to be" can be used to tell HOW something is (the condition = verb "ESTAR") and WHAT something is (the essence = verb "SER").
How is the apple? = Cómo está la manzana ?
It is unripe. = Está verde = In past time = WAS green = ESTABA verde.
What color is the apple? = De qué color es la manzana ?
It is green. = Es verde = In past time = WAS green = ERA verde.
In Spanish, a different verb is used to express "to be" depending on whether the speaker intends to address a condition or an essential quality.
To address condition, use ESTAR = is an irregular verb. It does not follow the standard rules of conjugation for regular verbs. Therefore, you must memorize it.
There are a few rules for deciding when to use SER or ESTAR in Spanish, if you need some grammar material about this subject, please tell me, and I can send it to you by mail.
Best wishes.
Sofía.