This is the 80th most frequent Finnish word.
pitäisi
"Should" or "ought to."
The word "pitäisi" is used here to express an obligation or recommendation for me to go to school.
Minun pitäisi mennä kouluun tänään.
I should go to school today.
The word "pitäisi" in interrogative form "pitäisikö" is used to suggest or question whether it would be appropriate for us to ask the teacher for help.
Pitäisikö meidän kysyä opettajalta apua?
Should we ask the teacher for help?
The word "pitäisi" is used here to express an expectation or assumption about the doctor knowing the best method of treatment.