Hi there!

So, let me try to explain what is the "sujeito indeterminado" for you, the expression literally means "unidetermined subject", in Portuguese it can happens in two cases:

1) When the verb is conjugated in the 3rd person of the plural

For example: Demoram muito para que sejamos atendidos.

(that means that in general it takes (demoram) a long time to "see" you in a public office for ex.)

DEMORAM - Demoram has no "antecedent", it doesn't refer to someone specifically but to something in general)

2) With the "particle" -SE with verbs in the 3rd person 

For example: Vive-se bem em São Paulo. 

(That means" ONE lives well in São Paulo)

I think that in both cases you could translate using "ONE..." to mark the unidetermined subject of the action. We're talking here about something in general or about a subject of a sentence which is not "identified", like in Vive-se bem em SP, Vive-se has no subject...

I hope I could help you!