This is the 303rd most frequent Finnish word.
riittää
"Riittää" means "to be enough" or "to suffice."
In this sentence, 'riittää' is used to express sufficiency or adequacy of amount.
Tämä annos riittää meille kaikille.
This portion is enough for all of us.
Here, 'riittää' conveys the idea of 'sufficient conditions' or satisfactory extent.
Riittää kun teet parhaasi.
It is enough if you do your best.
In this case, 'riittää' questions the adequacy or sufficiency of time for a specific purpose.