This is the 403rd most frequent Hebrew word.
מכיוון
Since; because.
Here, 'מכיוון' introduces the reason for why the individual is unable to come.
אני לא יכול לבוא היום, מכיוון שאני עסוק.
I can't come today because I am busy.
Here, 'מכיוון' introduces the cause for the change in plans.
תכננתי לטייל בשמש, אך מכיוון שהתחיל לרדת גשם, נשארתי בבית.
I planned to walk in the sun, but since it started raining, I stayed at home.
Here, 'מכיוון' explains the condition leading to the postponement of the class.