This is the 5422nd most frequent Portuguese word.
serviram
"Serviram" means "they served" or "you (plural) served" in English.
Here, 'serviram' is used to indicate the action of serving food or drinks carried out by the waiters in the past tense.
Os garçons serviram os convidados durante a festa.
The waiters served the guests during the party.
In this usage, 'serviram' reflects the act of serving or fulfilling duties towards the country, used in the context of military service, in the past tense.
No exército, os soldados serviram ao país com dedicação.
In the army, the soldiers served the country with dedication.
In this sentence, 'serviram' is used idiomatically to mean that the old books were useful or fulfilled a purpose, in the past tense.