is sure; is safe/secure
He is not sure.
Alemán está seguro de la victoria, ya que es una victoria moral.
Alemán is confident of victory, as it is a moral victory.
— Mother Night (1996)
Tom no está seguro cómo proseguir.
Tom isn't sure how to proceed.
Funciona, estamos a salvo, el país está seguro.
It works, we are safe, the country is safe.
Tom no está seguro si María tiene el virus.
Tom isn’t sure whether María has the virus.
Tom dijo que no está seguro que Mary pueda hacer eso.
Tom said he isn't sure Mary can do that.
Un barco en el puerto está seguro, pero los barcos no se construyeron para eso.
A ship in port is safe, but ships weren't built for that.
Tom está seguro.
Tom is sure.
No one is safe here.
John está seguro, el aire fresco es una cosa buena.
John is sure, fresh air is a good thing.