Мы увидели кита с корабля.

Because кита is the accusative singular form of the noun кит.

For animate masculine nouns in Russian, the accusative singular looks like the genitive singular. Since a whale is animate, you get:

• nominative: кит
• accusative: кита

So in Мы увидели кита, кита is the direct object: we saw a/the whale.

Compare:

• Я вижу стол = I see a table
• Я вижу кита = I see a whale

The difference happens because стол is inanimate, but кит is animate.

Увидели is the perfective past form of увидеть, while видели is the imperfective past form of видеть.

Here, увидели means something like:

• we caught sight of
• we saw as a completed event

So Мы увидели кита suggests a single completed action: at some moment, we saw the whale.

By contrast, Мы видели кита would usually mean:

• we saw the whale / we have seen the whale
• or we were seeing the whale

The exact English translation may still be just we saw the whale, but the Russian aspect gives a different viewpoint:

• увидели = the moment/result of seeing
• видели = the process/fact/experience of seeing

Because the subject is мы = we, and the verb is in the past plural.

In Russian past tense, verbs agree in number, and in the singular also in gender:

• я увидел = I saw (male speaker)
• я увидела = I saw (female speaker)
• мы увидели = we saw

So the -и ending shows that the subject is plural.

Корабля is genitive singular.

It appears after the preposition с in the sense of from/off:

• с корабля = from the ship / off the ship

The base form is:

• корабль = ship

Its genitive singular is:

• корабля

So the phrase literally means from the ship.

Both can relate to being on a ship, but they mean slightly different things.

• с корабля = from the ship, emphasizing the point from which something is seen
• на корабле = on the ship, emphasizing location

So:

• Мы увидели кита с корабля = We saw the whale from the ship
• Мы увидели кита на корабле would more naturally mean we saw the whale while on the ship, with more focus on where we were

In many contexts, both could work, but с корабля is very natural if the idea is looking out from the ship.

Because с often means from/off a surface or platform, while из means out of the inside of something.

A ship is normally thought of as something you are on, not inside, for this kind of situation. So Russian says:

• с корабля = from the ship
• с берега = from the shore
• с моста = from the bridge

Using из here would sound wrong or at least unnatural in this context.

In this sentence, the normal interpretation is that we were on the ship and saw the whale from there.

So с корабля is understood with the verb увидели, not with кита.

Russian does sometimes allow phrases that could be structurally ambiguous, but here the intended meaning is clear from normal usage and common sense. A phrase like кит с корабля would also be odd in meaning, since whales do not normally come from a ship.

So learners should understand this as:

• We saw the whale from the ship

Russian has no articles.

So кита can mean:

• a whale
• the whale

The difference is understood from context.

That is very normal in Russian. For example:

• Я купил книгу = I bought a book / the book
• Мы увидели кита = We saw a whale / the whale

English requires an article, but Russian does not.

No, Russian word order is fairly flexible.

Мы увидели кита с корабля is a normal, neutral order:

• Мы = subject
• увидели = verb
• кита = object
• с корабля = prepositional phrase

But you could also say:

• С корабля мы увидели кита
• Кита мы увидели с корабля

These versions may shift emphasis or topic, but the basic meaning stays similar because the cases show the grammatical roles.

The standard stress is:

• мы уви́дели кита́ с корабля́

More specifically:

• уви́дели
• кита́
• корабля́

Stress matters in Russian, so it is worth learning words together with their stress patterns.

Usually, yes, or at least it is very helpful.

In present tense, Russian verb endings often clearly show the person. But in the past tense, the verb shows gender and number, not person. So увидели by itself could mean:

• we saw
• you saw
• they saw

depending on context.

That is why including мы makes the subject explicit.