Breakdown of Wirst du heute ein Horoskop lesen?
ein
a, an (eine)
du
you (informal singular)
heute
today
lesen
to read
Questions & Answers about Wirst du heute ein Horoskop lesen?
Why is lesen at the very end of the sentence?
In the German future tense (Futur I), the helping verb werden (here conjugated as wirst) takes the normal verb position. The main action verb (lesen) is pushed to the very end of the sentence in its basic infinitive form.
Where does the word wirst come from?
It is the du (you) form of the irregular verb werden. In the future tense, werden acts as the helping verb meaning 'will'. Because it is irregular, the vowel changes for the second and third person singular, giving us du wirst and er/sie/es wird.
How does the word order show that this is a question?
To form a yes/no question in German, you move the conjugated verb to the very first position. A normal statement would be Du wirst heute ein Horoskop lesen (You will read a horoscope today), but swapping the subject and the verb to Wirst du... turns it into a question.
The horoscope is the direct object being read. Why is it ein Horoskop and not einen Horoskop?
You are exactly right that it is the direct object and requires the accusative case! However, the noun is neuter (das Horoskop). For neuter nouns, the accusative article doesn't change from the nominative form, so it stays as ein.