Having an apparently female voice describe herself as ocupado is poor pedagogy. Also, the last syllable of a recording is sometimes dropped on both the normal and slow version. So when you hear "Sí, estoy muy ocupad..." you have to to guess that the grammatical gender used corresponds to the apparent gender of the voice.
Regarding your lower comment, no. Just like having a teacher of the opposite gender, you can know that the word used for a female speaker so you just change the ending if applicable. Besides, when you learn a language, you don’t only learn words and sentences that apply to just you- you learn the opposite gender, adjectives that don’t describe you, places you don’t live in, and things you don’t use. That’s just part of learning a language, you’ll always need to know those words even if you’ll never describe yourself with feminine words.
The basic rule for "estar" and "ser" is as follows: "ser" is used for permanent states, whereas "estar" is for temporary states. For example: mood, location and current actions are temporary, therefore you use "estar". Estoy bien, estás ocupado, estamos en la escuela, están en el trabajo, está caminando, etc. Things like your gender, nationality, physical aspect (in general) doesn't change. Soy una mujer, eres un hombre, es español, somos estadounidenses, soy rubia (blonde), sois altos (I live in Spain, so I use "vosotros" as well). there are other rules, exceptions and more elaborate explanations, but this is a very good groundrule. I hope this helps!
Soy is a conjugation of the verb ser, which translates as "to be" in English. Estoy is a form of the verb estar, also translating as "to be". These verbs get used in different circumstances.
Ser is generally used to talk about identities, characteristics, or times of events:
- Soy Larry, su camarero. - I am Larry, your waiter.
- Eres muy simpática. - You are very nice.
- La reunión es el sábado. - The meeting is on Saturday.
Estar, on the other hand, is used to describe states and conditions, so traits that are not inherent to the object you're talking about. It's also used to talk about the location of objects:
- Está oscuro fuera. - It is dark outside.
- Estoy muy enfermo. - I am very ill.
- La niña está en el jardín. - The girl is in the garden.
Soy is the yo form of ser, and you use ser for things like professions, descriptions, and other permanent traits.
Estoy is for temporary things, like feelings or location. You would say "estoy feliz" (I am happy), not "soy feliz," because the latter would mean you are happy all the time, as a permanent part of your identity. In middle school, my Spanish teacher gave us a nice rhyme to remember that might help: "how you feel and where you are, always use the verb estar."
No, because “muy” (very) isn’t an adjective in this sentence and “ocupado” (busy) isn’t a noun. “Muy” is an adverb because it modifies an adjective - adverbs modify anything that isn't a noun. In this case, the adjective is “ocupado.” If you said “sí, estoy ocupado muy,” you’d be saying “yes, I am busy very,” which is not correct.