This is the 740th most frequent Vietnamese word.
mỗi
"Each" or "every."
In this sentence, 'mỗi' is used to mean 'every' to express regularity and interval.
Anh ấy đến thăm chúng tôi mỗi ngày.
He visits us every day.
Here 'mỗi' is used to mean 'each' to specify individuality within a group.
Mỗi người đều có một câu chuyện riêng.
Everyone has their own story.
In this case, 'mỗi' is combined with 'lần' to mean 'every time', indicating each occurrence of an event.