Puu kuoli viime talvena.

Finnish has no articles, so there is no separate word for the or a/an.

So puu can mean:

• a tree
• the tree

Which one is meant depends on context. In a short standalone sentence like this, English might translate it either way depending on the situation.

Kuoli is the past tense, 3rd person singular form of the verb kuolla (to die).

So:

• kuolla = to die
• hän kuoli = he/she died
• puu kuoli = the tree died

The ending is not added in the same simple way as in English, so this is something you learn as part of the verb’s conjugation pattern.

Because kuolee is the present tense, while kuoli is the past tense.

Compare:

• Puu kuolee. = The tree dies / is dying
• Puu kuoli. = The tree died

Since the sentence refers to last winter, the past tense is needed.

Talvena is the essive case of talvi (winter).

In expressions of time, the essive is often used to mean during a certain time period. So:

• talvi = winter
• talvena = in/during winter

That is why viime talvena means last winter.

This is a very common Finnish time expression pattern:

• viime vuonna = last year
• viime kesänä = last summer
• viime talvena = last winter

Because viime is one of those words that usually does not change its form in these expressions.

Even though talvi changes to talvena, viime stays viime:

• viime talvena
• viime vuonna
• viime kesänä

So this is normal Finnish usage, not a mistake.

It means last winter, referring to the previous winter period.

More literally, you can think of it as during the last winter.

It does not usually mean one exact moment. It refers to the time period when something happened.

Yes. Finnish word order is more flexible than English word order.

For example, these are all possible:

• Puu kuoli viime talvena.
• Viime talvena puu kuoli.

The basic meaning stays the same, but the emphasis changes a little.

• Puu kuoli viime talvena puts the sentence forward in a neutral way.
• Viime talvena puu kuoli emphasizes the time more, like Last winter, the tree died.

Yes. In Finnish, kuolla is used for living things in general, including plants and trees.

So a tree can kuolla, just as a person or an animal can.

In English, learners sometimes wonder whether die sounds strange for a tree, but in both Finnish and English it is perfectly natural.

Kuolla is intransitive, which means it does not take a direct object.

So:

• Puu kuoli. = The tree died.

But if you want to say that something caused the death, Finnish usually uses another verb, such as:

• tappaa = to kill

So:

• Myrsky tappoi puun. = The storm killed the tree.

That is different from:

• Puu kuoli. = The tree died.

You know from context, not from an article.

Finnish leaves this open unless something else makes it clear. So puu could mean:

• a tree if you are introducing it
• the tree if it is already known from context

That is normal in Finnish. English forces you to choose; Finnish often does not.

Yes, basically. Kuoli is in the Finnish past tense (often called the imperfect), and in a sentence like this it corresponds well to English died.

So the tense match is straightforward here:

• Puu kuoli viime talvena. = The tree died last winter.

Finnish does have other past forms, but this is the normal one for a completed event in the past.