Paita on hengittävä.

• paita = shirt
• on = is (the he/she/it form of olla, to be)
• hengittävä = breathable

So the structure is very straightforward: subject + verb + adjective.

Finnish does not have articles like English a/an and the.

So paita can mean:

• a shirt
• the shirt
• sometimes just shirt, depending on context

You learn which meaning is intended from the situation, not from a separate article word.

Paita is in the nominative singular.

Here, it is the subject of the sentence, so nominative is the normal form:

• Paita on hengittävä. = The shirt is breathable.

The basic dictionary form of the noun is also paita, so this sentence uses the basic singular subject form.

On is the third-person singular form of olla (to be).

A quick comparison:

• minä olen = I am
• sinä olet = you are
• hän on = he/she is
• se on = it is

Since paita is a singular thing, Finnish uses on:

• Paita on hengittävä.

Here hengittävä is a predicate adjective-like form describing paita.

With a singular subject, Finnish commonly uses this basic singular form:

• Paita on hengittävä.

A useful comparison:

• Paita on hyvä. = The shirt is good.
• Paita on kallis. = The shirt is expensive.
• Paita on hengittävä. = The shirt is breathable.

So hengittävä is simply the form that fits this singular sentence pattern.

Yes. Hengittävä comes from hengittää, which means to breathe.

The ending -va / -vä often makes a form that means something like:

• doing X
• that does X
• or, in some contexts, a quality associated with that action

So hengittävä is literally something like breathing, but in normal product/clothing language it means breathable.

This is very common in Finnish:

• johtaa = to lead → johtava = leading
• pestä = to wash → pestävä = washable
• hengittää = to breathe → hengittävä = breathable

Because of vowel harmony, an important Finnish sound pattern.

Finnish words with front vowels like ä, ö, y usually take endings with front vowels too. Since hengittää contains ä, the ending appears as -vä, not -va.

So:

• hengittävä is the natural harmonic form

This is a very normal Finnish pattern.

Grammatically, yes, but it means something different.

• Paita on hengittävä = The shirt is breathable
• Paita hengittää = The shirt breathes

The second one sounds much more literal, almost as if the shirt itself is doing the action of breathing. For clothing and materials, Finnish normally uses hengittävä when talking about breathability.

The neutral word order is:

• Paita = subject
• on = verb
• hengittävä = description/predicate

So:

• Paita on hengittävä.

This is the most natural basic order for a simple statement. Finnish word order can change for emphasis, but this version is the standard, unmarked one.

The noun and verb change like this:

• Paita on hengittävä. = The shirt is breathable.
• Paidat ovat hengittäviä. = The shirts are breathable.

Notice:

• paita → paidat (shirt → shirts)
• on → ovat (is → are)
• hengittävä → hengittäviä

That last change is part of how Finnish typically handles predicate adjectives with plural subjects.

A rough guide is:

hen-git-tä-vä

A few tips:

• h is always pronounced
• tt is a long/double t
• ä is not the same as English a; it is a front vowel, somewhat like the vowel in British cat, but cleaner and shorter
• the final -vä should clearly include ä, not a

A rough English-friendly approximation would be:

HENG-git-tuh-vuh

But that is only approximate. The real Finnish vowels are more precise and pure than English ones.