The verb is FICAR as Felipe said, I agree with him. Many times FICAR is used as became or turn. It is about status and conditions. The copy is in a good condition. /A cópia ficou boa/A cópia está em boas condições. Ele ficou triste (His condition somehow was changed to a said one) When we use FICAR instead of ESTAR we are focusing on the process/agent that has caused the state/status change. I think it is like "come out" too. Não sei como esta explicação vai ficar/I am not sure how this explanation will come out.

it's because it's another verb: Ficar. conjugation: http://www.conjuga-me.net/verbo-ficar . "ficar" doesn't have a direct translation to english. depending on the context, it can mean: * "to stay" (eu fiquei em casa); * "to be" (a cópia ficou boa?). note that there is a small difference between saying "a cópia ESTÁ boa" and "a cópia FICOU boa". in the second one, it's more like you're saying "the copy ended up well"; * in popular language (at least in brazil), "ficar" can also mean "to date/to make out" (eles ficaram na festa).

"Ficou" is the 3rd person of the singular (he/she/it or in portuguese ele/ela) of the verb "Ficar" in the past simple (pretérito perfeito simples). The most common translation of "FICAR" is "STAY it depends on the content as it can varie. Ex: "A menina ficou em casa." (The girl STAYED home). "Ele ficou comigo." (He STAYED with me.) " O noivo ficou pronto em 5 minutos." (The groom GOT ready in 5 minutes). So, as you can see there can be a slight difference according to the context. The conjugation of the verb is as follows: Eu fiquei Tu ficaste Ele/Ela/Você ficou Nós ficámos Vocês/Eles/Elas ficaram