This is not a slang term, but a popular saying in Spanish which means 'Death is the only certainty we have in life'. It is used to express the inevitability of death in our lives.
Examples
- Spanish: Siempre recuerdo que la muerte es lo único seguro que tenemos en la vida, así que trato de vivir al máximo cada día.
- English: I always remember that death is the only certainty we have in life, so I try to live each day to the fullest.