The verb to be in Portuguese has a few possible translations; the main two are SER and ESTAR but you also have FICAR and ANDAR. Here are a few tips to help you choose which one to use:
The verb ser is used for conditions or characteristics that are permanent and the verb estar is used for transitory or non-permanent conditions or characteristics.
For example compare these two sentences:
Maria é bonita (Maria is beautiful) – Maria is always beautiful.
Maria está bonita (Maria is beautiful) – Maria is beautiful at this moment in particular.
The verb ser is used to express something permanent, as a guide remember to use ser for the following:
a) Nationality
b) Profession or marital status
c) Telling the time
d) Possession
e) Personality traits
f) What something is made of
g) Geographical location (unchanging)
Examples:
Ela é americana. She is American
Sou artista. I am an artist
O Brasil é na América do Sul. Brazil is in South America
The verb estar is used for temporary conditions, as a guide remember to use estar for the following:
a) Location (variable)
b) Weather on a particular day or time
c) With an adjective that is for a temporary state or mood
Examples:
Como estás hoje? Estou bem, obrigada. How are you today? I’m fine, thanks.
Onde está o Pedro? Where is Pedro?
Estou com fome. I’m hungry.
The verb ficar is also used when expressing location and in the sense of staying or remaining.
Examples:
Onde fica o mercado? – Where is the market?
Angola fica na Africa. – Angola is in Africa.
Fico em casa – I stay at home.
And finally, the verb andar can also be used to mean to be, when what you are describing is a feeling or action that is prolonged to the moment of the sentence. It can take the sense of ‘has been’ or will be’.
Examples:
Anda pensando no que fazer – She has been thinking about what to do.
Ele anda muito preocupado ultimamente. – He has been really worried lately.
Andaremos em acabar isso hoe – We will be finishing that today.
I hope that helps you decide which verb to use.