Tarkistan uutisen lähteen.

Tarkistan is the 1st person singular present tense form of the verb tarkistaa.

So:

• tarkistaa = to check, to inspect, to verify
• tarkistan = I check / I am checking

The ending -n is the usual marker for I in Finnish present tense:

• minä tarkistan = I check

In Finnish, the pronoun minä is often left out because the verb ending already shows the subject.

Uutisen is the genitive singular of uutinen.

Here it means something like:

• uutinen = news item, article, report
• uutisen lähde = the source of the news item/article

So uutisen shows a relationship similar to English of:

• uutisen lähde = source of the news

This is very common in Finnish:

• talon ovi = the door of the house
• kirjan nimi = the name of the book
• uutisen lähde = the source of the news

Also note the stem change:

• uutinen -> uutise- -> uutisen

This is normal for many -nen nouns.

In this sentence, lähteen is the object of the verb tarkistan, and it appears in the genitive singular.

So:

• lähde = source
• lähteen = the source as a total object

Finnish often uses the genitive for a singular total object in an affirmative sentence.

That means the action is viewed as directed at the whole object:

• Tarkistan uutisen lähteen. = I check the source of the news.

The idea is that you are checking that specific source as a whole, not just doing some vague or partial checking.

They both end in -n, but their roles are different.

• uutisen is genitive because it modifies lähteen:
  uutisen lähde = the source of the news
• lähteen is genitive because it is the total object of tarkistan

So the structure is roughly:

• [uutisen] [lähteen]
• [of the news] [the source (as object)]

This is a good example of how the same case ending can serve different functions in the same sentence.

Yes, but it changes the nuance.

• Tarkistan uutisen lähteen.
  = I check the source (a complete, bounded object)

• Tarkistan uutisen lähdettä.
  = I am checking the source / I’m checking at the source in a more ongoing, incomplete, or partial sense

The partitive object (lähdettä) is often used when the action is:

• incomplete
• ongoing
• indefinite
• only affecting part of something

So the original sentence with lähteen sounds more like a normal, complete action: I check the source.

Usually uutinen means a news item, a news story, or an article/report, not news in general.

So:

• uutinen = one piece of news
• uutiset = the news / news bulletin / news items

That means uutisen lähde most naturally means:

• the source of the news story
• the source of the report/article

If you wanted the source of the news in a broader general sense, Finnish might use a different phrasing depending on context.

Yes. Uutinen is one of the very common Finnish nouns ending in -nen.

These nouns usually change like this:

• nominative: uutinen
• genitive: uutisen
• partitive: uutista

The -nen changes to -se- in many forms:

• nainen -> naisen
• ihminen -> ihmisen
• uutinen -> uutisen

This is a pattern learners see very often, so it is worth getting used to early.

Yes. This is a very normal and natural Finnish structure.

Finnish often expresses X of Y by putting Y in the genitive before X:

• kirjan kansi = the cover of the book
• elokuvan nimi = the name of the movie
• uutisen lähde = the source of the news

So instead of using a separate word like English of, Finnish usually uses word order plus the genitive ending.

Yes, but the neutral word order here is very natural:

• Tarkistan uutisen lähteen.

This is the standard verb + object order.

You could change the order for emphasis, for example:

• Uutisen lähteen tarkistan.

That sounds marked, as if emphasizing the source of the news specifically.

For a learner, the original sentence is the safest and most natural version.

It can mean several related things, depending on context:

• check
• inspect
• verify
• look over

So Tarkistan uutisen lähteen could mean:

• I check the source of the news story.
• I verify the source of the report.

The exact English translation depends on context, but the core idea is examining something to make sure it is correct, reliable, or suitable.

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

So:

• uutinen can mean a news item or the news item
• lähde can mean a source or the source

The exact meaning is understood from context.

In this sentence, English usually translates it with the:

• I check the source of the news/story

because the context suggests a specific source connected to a specific news item.

Finnish stress is usually very regular: it falls on the first syllable of each word.

So:

• TAR-kis-tan
• UU-ti-sen
• LÄH-teen

A rough pronunciation guide:

• Tarkistan ≈ TAHR-kis-tahn
• uutisen ≈ OO-ti-sen
• lähteen ≈ LAEH-teen

A few helpful points:

• uu is a long vowel, like a longer oo
• äh in läh- is a front vowel sound that English does not have exactly
• ee in lähteen is long

Finnish pronunciation is usually quite consistent once you know the letter sounds.