This is the 1194th most frequent Portuguese word.
disseram
"Disseram" means "they said" in English.
In this sentence, 'disseram' is used as the third-person plural past of 'dizer', meaning 'they said', indicating an action that was completed in the past.
Eles disseram que chegariam mais tarde.
They said they would arrive later.
Here, 'disseram' conveys the pronouncement from an unspecified subject in past tense, implying an indirect communication or report made to the speaker.
Me disseram que você precisava de ajuda.
They told me that you needed help.
'Disseram' here is metaphorically assigned to 'the news', in the third-person plural, suggesting personified communication by media sources.