Here's how to say it depending on what you love:
* Eu amo meu filho/minha filha: I love my son/daughter
* Eu amo meu marido/minha esposa: I love my husband/wife
* Eu amo meu pai/minha mãe: I love my father/mother
* Eu amo meu cachorro/minha gata: I love my dog/cat
* Eu amo meu carro/minha casa: I love my car/house
Important Note: "Eu amo" (I love) can be used to express love for romantic partners, family, friends, pets, and possessions.
Let me know if you want to express "I love you" in Portuguese, or if you have any other questions!