This is the 14825th most frequent Russian word.
поблагодарили
"Thanked."
The word 'поблагодарили' is in the past tense and indicates that the action of thanking was completed, with the subject being 'они' (they).
Они поблагодарили учителя за помощь.
They thanked the teacher for the help.
Here, 'поблагодарили' conveys the act of expressing gratitude accomplished by 'дети' (children) towards their parents.
Дети поблагодарили родителей за поездку.
The children thanked their parents for the trip.
The usage of 'поблагодарили' here signifies the collective action done by 'мы' (we) towards a group of individuals.