"Yo estoy bien."
Translation:I am fine.
estar for condition (now) = estoy bien, since five minutes from now he can get run over by a car and be, well, no longer fine
Soy(verb ser) is used to describe innate, permanent conditions, which is different from estoy(verb estar-temporary state)
"Estoy" means «I am in a place», «I am doing something» or «I feel…»; and "Soy" means «I am something». Examples:
- Estoy en la biblioteca = I am in the library
- Estoy comiendo = I am eating
Estoy enfermo = I am sick
Soy un chico = I am a boy
- Soy alto = I am tall
I sometimes think of estar to be used for feelings. It gets much more complicated but on a general rule of thumb you usually use estar to describe how you feel instead of ser
Because it is incorrect (even if DL is marking it as correct).
"Soy bueno."- I am good (meaning a good person).
"Estoy bien."- I am well (indicating my feeling at this exact moment in time).