This is the 19th most frequent Portuguese word.
tem
"Tem" means "has" or "there is/are" (depending on context).
Here, 'tem' is the verb 'ter' conjugated in the third person singular present tense, used to indicate possession.
Ele tem um carro muito bonito.
He has a very nice car.
In this case, 'tem' is used impersonally to mean 'there is,' referring to the existence of something.
Tem um livro na mesa.
There is a book on the table.
Here, 'tem' is part of the expression 'tem que,' which is used to indicate necessity or obligation.