This is the 152nd most frequent Portuguese word.
seis
"Seis" means "six" in English.
Here, 'seis' is used as a cardinal number to indicate quantity, referring to the amount of hours.
Eu estive no trabalho por seis horas hoje.
I have been at work for six hours today.
In this sentence, 'seis' refers to the time, indicating the hour for the event.
Hoje iremos ao concerto às seis.
Today we will go to the concert at six.
Here, 'seis' is used as a quantifier to specify the number of students discussed.