This is the 926th most frequent Portuguese word.
haver
"To exist," "to have" (auxiliary verb), or "there is/are."
The word "há" is used impersonally, equivalent to "there is" in English, denoting the existence or occurrence of the meeting.
Há uma reunião agendada para amanhã.
There is a meeting scheduled for tomorrow.
"Haver" is used in the infinitive form to indicate existence or necessity, combined with "dever" to express necessity or a suggestion.
Deveria haver mais empenho por parte dos alunos.
There should be more effort on the part of the students.
"Haver" is used to question the existence or amount of something, coupled with "devem" to express estimation.