Hopefully you already learned that, but nevertheless someone else might need it. Pronto/pronta is an adjective, not a verb. Only verbs conjugate for person (and number). Adjectives (and pronouns/determiners) decline for gender and number (reflecting nouns). Adverbs, conjunctions, interjections and prepositions do not inflect.
- sono, sei, è, siamo, siete, sono (person+number conjugation)
- pronto, pronta, pronti, pronte (gender+number declination)
- quasi (no inflection)
Since it ended with an I, I thought it would be they because I usually means plural.
That works for adjectives and participles and here quasi is an adverb, but you could say sono quasi pronti :)
Similar to @MickeytheGreat, I put "they are almost ready" because I thought the quasi would indicate a plural and also that pronta would be pronto if talking about yourself - io pronto. So is the pronta here representing a female speaking?
I wrote "they ....." because of the third person in plural, but , we are learning. ....
Not clear from the discussion below why the man says Sono quasi pronta. They might want to wonder if they should make the recordings gender appropriate. We have also heard the man say "I am Maria." Interesting that the people doing the recordings didn't seem to notice the oddness of this.....