Ompelija sanoi, että takin sauma on melkein auki.

sanoi is the past tense (more specifically, the simple past / imperfect) of sanoa = to say.

• sanoa = infinitive
• hän sanoo = he/she says
• hän sanoi = he/she said

So:

• Ompelija sanoi = The tailor / seamstress said

The ending is not added in a very transparent “English-like” way, so this is a form you learn as part of Finnish verb conjugation.

In Finnish, a comma is normally used before että when it introduces a subordinate clause.

So the sentence is divided into:

• Ompelija sanoi = main clause
• että takin sauma on melkein auki = subordinate clause

This is very standard Finnish punctuation.

että introduces a subordinate clause and usually corresponds to English that.

So:

• Ompelija sanoi, että... = The tailor said that...

In English, that is often optional:

• The tailor said the jacket’s seam is almost open.

But in Finnish, että is normally expressed when you build this kind of clause.

takin is the genitive singular of takki (jacket, coat).

• takki = a jacket / the jacket
• takin = of the jacket / the jacket’s

Here it shows possession or association:

• takin sauma = the jacket’s seam / the seam of the jacket

This is a very common Finnish structure:

• talon ovi = the house’s door
• auton väri = the car’s color
• takin sauma = the jacket’s seam

Because sauma is the subject of the subordinate clause:

• takin sauma on melkein auki
• the jacket’s seam is almost open

In that clause:

• takin = genitive modifier (of the jacket)
• sauma = subject
• on = is
• melkein auki = almost open

So Finnish marks the owner/modifier with the genitive (takin), but the main noun being talked about stays in the nominative (sauma).

auki is a common Finnish word meaning open in the sense of being in an open state.

It is often used with olla (to be):

• Ovi on auki. = The door is open.
• Kauppa on auki. = The store is open.
• Sauma on auki. = The seam is open.

For learners, the most useful thing is to treat auki as a fixed state word used in expressions like olla auki.

In this sentence, melkein auki means almost open or, more naturally here, almost coming apart / almost split open.

Because melkein (almost) modifies auki.

• melkein auki = almost open

This is the normal placement in Finnish, just as in English:

• almost open
• melkein auki

So the phrase works as one unit describing the state of the seam.

on is the 3rd person singular of olla = to be.

• minä olen = I am
• hän on = he/she is

Here the clause is:

• takin sauma on melkein auki
• the jacket’s seam is almost open

So on links the subject (sauma) with its state (melkein auki).

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

So words like:

• ompelija
• takki
• sauma

do not automatically include an article. Whether English uses a or the depends on context.

For example:

• ompelija can mean a tailor / the tailor
• sauma can mean a seam / the seam

In this sentence, context tells us which English article sounds natural.

Not by itself. Finnish nouns usually do not show grammatical gender.

So ompelija can mean:

• tailor
• seamstress
• sewer (someone who sews)

depending on context.

Finnish also uses hän for both he and she, so gender is often left unspecified unless it matters.

Yes, but the given version is very neutral and natural.

For example, the subordinate clause could be rearranged a little:

• Ompelija sanoi, että sauma on takissa melkein auki.

But that changes the structure slightly and is less straightforward than takin sauma.

The original:

• Ompelija sanoi, että takin sauma on melkein auki.

is a clear, standard way to say it.

Yes. Finnish very often uses this pattern:

• owner/modifier in the genitive + main noun

Examples:

• pojan kirja = the boy’s book
• talon katto = the roof of the house
• takin sauma = the seam of the jacket

This is one of the most important basic noun structures in Finnish.

Because auki behaves differently from ordinary inflecting adjectives. It is commonly used as an invariable state expression.

Compare:

• ovi on suuri = the door is big
  
  • suuri is a regular adjective

But:

• ovi on auki = the door is open
  
  • auki is used as a fixed state word and does not change here

So even though it translates like an adjective in English, it does not behave exactly like a regular adjective in Finnish grammar.

It breaks down like this:

• Ompelija = subject
• sanoi = verb
• että takin sauma on melkein auki = content clause introduced by että

Inside the content clause:

• takin = genitive modifier
• sauma = subject
• on = verb
• melkein auki = predicative expression

So the sentence has a very common Finnish pattern:

[Someone] + said + that + [clause]