Breakdown of Ты понимаешь этот текст?
ты
you (singular)
текст
text
этот
this [f: эта, n: это]
понимать
to understand
Questions & Answers about Ты понимаешь этот текст?
Why does the verb end in -ешь?
The dictionary form of the verb is понимать (to understand). Because it is a regular first conjugation verb ending in -ать, you drop the -ть and add the ending -ешь to match the informal singular pronoun ты (you).
Is этот текст in the nominative or accusative case here?
It is in the accusative case because it is the direct object (the thing being understood). However, for masculine inanimate nouns like текст, the accusative form looks exactly the same as the dictionary (nominative) form. Because the noun doesn't change, the word for 'this' (этот) stays the same too.
Where is the word for 'Do' in the Russian sentence?
Russian does not use helper verbs like 'do' to ask questions. You just take the normal statement (Ты понимаешь этот текст) and turn it into a question using a question mark in writing, or by raising the pitch of your voice on the key word when speaking.
If I wanted to ask a stranger this question, what would change?
You would use the formal 'you', which is вы. Because the pronoun changes, the verb ending must also change to match it. The sentence would become: Вы понимаете этот текст?