This is the 682nd most frequent Finnish word.
tulleet
"Have come" or "came" (past participle of "tulla").
Here, 'tulleet' is used as a form of a verb in the past perfect tense, indicating that they had completed the action of coming.
He olivat juuri tulleet takaisin matkaltansa.
They had just come back from their trip.
In this instance, 'tulleet' indicates the past action of the packages arriving, related to their completion.
Pakettit ovat tulleet postitse tänä aamuna.
The packages have arrived by mail this morning.
Here, 'tulleet' is part of an idiomatic expression indicating the enactment of new rules.