This is the 394th most frequent Hebrew word.
היינו
"We were" or "that is to say."
The word "היינו" means "we were" in past tense and is used here to describe a state of being in the past.
בתקופה ההיא היינו ילדים קטנים ושיחקנו בחצר כל יום.
In those times, we were little children and played in the yard every day.
Here, "היינו" is used in a conditional sense, referring to a hypothetical agreed-upon state.
היינו מסכימים עם ההצעה, אך היו לנו הסתייגויות מסוימות.
We would have agreed with the proposal, but we had certain reservations.
The word "היינו" is part of the phrase indicating a past state combined with a modal verb, showing an action that was necessary in the past.