Learn Spanish (Latin America): Estoy muy bien hoy.

We use estoy (from the verb estar) because it describes how you feel right now. In Spanish, we use ser (like soy) for more permanent traits or your identity, but estar is used for temporary states, locations, and health.

What question word from this lesson would prompt this sentence?

Someone would ask ¿Cómo estás? (How are you?). The question word cómo means "how". The sentence estoy muy bien hoy is the standard way to answer that question!

Could I say estoy muy bueno instead of estoy muy bien?

You usually shouldn't! Bien means "well", which correctly describes your health or mood. Bueno means "good". If you say estoy muy bueno, in many Spanish-speaking countries it actually translates to "I am very physically attractive"! So to say you are doing fine, always stick to estoy bien.

Why isn't the word yo (I) at the beginning of the sentence?