Wieczorem oglądam wiadomości w telewizji.

Wieczór is the basic dictionary form meaning evening.

In the sentence, wieczorem means in the evening or this evening. It is an adverbial time expression built from the noun. Polish often does this with parts of the day or seasons.

So:

• wieczór = evening
• wieczorem = in the evening

You would not normally say w wieczór for this meaning.

It depends on context.

With a present-tense verb like oglądam, the sentence often sounds habitual, so a natural English meaning is In the evening / In the evenings, I watch the news on TV.

But in the right context, wieczorem can also mean this evening.

If you want to make the repeated meaning especially clear, Polish often uses wieczorami, meaning in the evenings.

Because the verb already shows the subject.

Oglądam ends in -am, which tells you the subject is I. Polish often leaves out subject pronouns when they are clear from the verb form.

So:

• oglądam = I watch / I am watching
• ja oglądam = I watch, with extra emphasis on I

You only add ja if you want contrast or emphasis.

Oglądam is the 1st person singular present tense form of oglądać.

So:

• oglądać = to watch / to look at
• oglądam = I watch / I am watching

This verb is imperfective, which is the normal choice for:

• repeated actions
• ongoing actions
• general habits

That fits this sentence well.

In Polish, wiadomości is a plural word.

It literally relates to items of information / messages, and in everyday usage it commonly means:

• the news
• the news program
• news reports

So even though English uses the singular-looking word news, Polish uses wiadomości.

Also note:

• wiadomość = message, piece of information
• wiadomości = messages / news

It actually is the object, so it is in the accusative case after oglądam.

The important point is that in Polish, some nouns have the same form in nominative and accusative. That is what happens here.

So in this sentence:

• oglądam wiadomości = I watch the news

Even though the form looks the same, its grammatical role is still object.

Here w means in / on, and it requires the locative case in this usage.

The noun is:

• telewizja = television

After w, it becomes:

• w telewizji

So telewizji is the locative singular form of telewizja.

Yes. Idiomatically, w telewizji means on TV / on television.

That is just how Polish expresses the medium here.

So:

• oglądam wiadomości w telewizji = I watch the news on TV

If you meant physically inside the TV set, you would use a different word, such as telewizor.

Yes, but it means something slightly different.

• oglądam telewizję = I watch TV
• oglądam wiadomości w telewizji = I watch the news on TV

In your sentence, the object is specifically wiadomości, and w telewizji tells you where/by what medium you watch them.

Yes. Polish word order is quite flexible.

Your sentence is a very natural, neutral order:

• Wieczorem oglądam wiadomości w telewizji.

But you could also say:

• Oglądam wieczorem wiadomości w telewizji.

The basic meaning stays the same, but the emphasis can shift a little. Putting Wieczorem first makes the time frame the starting point of the sentence.

Polish does not have articles like a or the.

So Polish simply says:

• oglądam wiadomości

and the listener understands from context whether that means news, the news, or sometimes some news.

In this sentence, the most natural English translation is the news, even though Polish does not use a separate word for the.