This is the 427th most frequent Hebrew word.
עלינו
"Upon us" or "it is incumbent upon us."
Again, 'עלינו' indicates responsibility or a required action.
עלינו להתעורר מוקדם מחר.
We need to wake up early tomorrow.
Here, 'עלינו' conveys obligation or necessity.
עלינו ללמוד בכל יום.
We must study every day.
In this case, 'עלינו' refers to something being physically above or over us.