Breakdown of Он аккуратно ставит поднос на диван.
он
he / it (for a masculine noun) / it (for a neuter noun)
на
on, at / by (transport) / to (a place) / to (in answer to)
диван
sofa, couch
ставить
to put, stand (upright)
Questions & Answers about Он аккуратно ставит поднос на диван.
Why do we use ставит to mean "puts" here instead of кладёт?
In Russian, how you "put" something depends on its orientation. Класть means to lay something flat, while ставить means to stand something up on its base. A tray (поднос) is considered to have a base that it rests on, so you use ставить to put it down in its natural functional position.
Why is it на диван (Accusative) instead of на диване (Prepositional)?
Because ставить is an action that involves moving an object to a new destination. When the preposition на indicates the direction of motion ("onto the sofa"), it takes the Accusative case. If you were describing the tray already resting there without motion (using the intransitive state verb стоять), you would use the Prepositional case: поднос стоит на диване.
Is поднос the direct object? Why doesn't its ending change?
Yes, поднос is the direct object being put on the sofa, so it is in the Accusative case. However, because it is a masculine, inanimate noun (an object, not a living person or animal), its Accusative form looks exactly the same as its dictionary (Nominative) form.
Does аккуратно mean "accurately"?
Аккуратно is a classic "false friend" for English speakers. It doesn't mean "accurately" (which is usually точно). Instead, it translates to "neatly," "carefully," or "tidily." Here, he is setting the tray down with care so nothing spills.