Toukokuu on kiireinen kuukausi, koska lukuvuosi on melkein lopussa.

Toukokuu is the subject of the sentence, so it appears in the basic dictionary form, called the nominative.

Finnish does not have articles like English a/an or the. So:

• toukokuu = May
• kuukausi = month
• kiireinen kuukausi = a busy month / the busy month, depending on context

Finnish leaves that distinction to context rather than marking it with a separate word.

On is the third-person singular form of the verb olla, which means to be.

So:

• Toukokuu on kiireinen kuukausi = May is a busy month
• lukuvuosi on melkein lopussa = the school year is almost over / at the end

Because both toukokuu and lukuvuosi are singular subjects, the verb is on in both parts of the sentence.

This is a very normal Finnish structure.

• kiireinen = busy
• kuukausi = month

Together they mean a busy month.

Finnish often uses:

• adjective + noun

So:

• kiireinen kuukausi = busy month
• pitkä päivä = long day
• hyvä kirja = good book

The noun is still needed because kiireinen only describes what kind of thing it is.

Kiireinen is an adjective meaning busy. It is in the nominative singular because it describes kuukausi, which is also nominative singular.

In Finnish, adjectives usually agree with the noun they describe in number and case.

So here:

• kiireinen kuukausi = both singular nominative

If the noun changed form, the adjective would usually change too. For example:

• kiireisessä kuukaudessa = in a busy month

So the form kiireinen is used because the noun it describes is in the basic singular subject form.

Koska means because in this sentence.

It introduces a reason:

• Toukokuu on kiireinen kuukausi = the main statement
• koska lukuvuosi on melkein lopussa = the reason why

So the whole sentence means:

• May is a busy month, because the school year is almost over.

Be careful: koska can also mean when in some contexts, especially in questions or older/literary usage, but in modern everyday sentences like this one, it very commonly means because.

Yes, lukuvuosi is one word, and it is a compound noun, which Finnish uses very often.

It is made from:

• luku = study / reading
• vuosi = year

Together:

• lukuvuosi = school year / academic year

Finnish forms many ideas by combining nouns into one word, where English might use two words:

• koulu + kirja → koulukirja = schoolbook
• työ + päivä → työpäivä = workday
• luku + vuosi → lukuvuosi = school year

This is one of the most important things to notice in the sentence.

• loppu = end
• lopussa literally means in the end or at the end

The ending -ssa/-ssä is the inessive case, often meaning in.

So:

• lukuvuosi on lopussa

literally means something like:

• the school year is in its end-stage
• more naturally: the school year is ending / almost over

Finnish often uses location-type cases in expressions where English uses something more abstract. This is one of those very common patterns.

Melkein means almost.

So:

• lopussa = at the end / ending
• melkein lopussa = almost at the end / almost over

This is a very natural Finnish way to say that something is close to finishing.

Examples:

• Elokuva on melkein lopussa. = The movie is almost over.
• Ruoka on melkein valmis. = The food is almost ready.

So in your sentence, lukuvuosi on melkein lopussa means the school year is very near its end.

Yes, Finnish word order can change more than English word order, but this sentence uses the most neutral, standard order:

• Toukokuu (subject)
• on (verb)
• kiireinen kuukausi (predicate)
• koska... (reason clause)

And in the second clause:

• lukuvuosi (subject)
• on (verb)
• melkein lopussa (predicate/adverbial expression)

This is the clearest and most neutral way to say it.

Finnish can move words around for emphasis, but learners should usually start with this normal pattern:

• subject + verb + other information

So this sentence is a good model of basic Finnish sentence structure.

Because this is a basic equational sentence: X is Y.

• Toukokuu on kiireinen kuukausi.

Here, kiireinen kuukausi is a predicate noun phrase describing what May is. In this kind of sentence, the predicate is often in the nominative when the subject is singular and the sentence is affirmative.

So:

• Toukokuu on kiireinen kuukausi.
• Hän on opettaja. = He/She is a teacher.

The partitive is used in some other predicate situations, especially with plural subjects, mass nouns, or incomplete/ongoing meanings, but not in this simple singular identity/description sentence.

By itself, Toukokuu on kiireinen kuukausi usually sounds general:

• May is a busy month

That is, May is being described as a type of month in general, often because of what usually happens then.

If you wanted to make it more clearly about a specific May, the context would usually show that. Finnish often relies on context rather than adding articles like English does.

So in most cases, a learner should understand this sentence as a general statement:

• May is a busy month, because the school year is almost over.

Yes. Finnish and English do not always match word-for-word, so several English translations are possible:

• the school year is almost over
• the school year is almost at an end
• the school year is nearly over
• the school year is close to ending

The most natural translation in everyday English is usually:

• the school year is almost over

That is often the best choice, even though the Finnish structure is literally closer to is almost at the end.