Znalazłam to mieszkanie przez ogłoszenie w internecie, a jego lokalizacja od razu mi się spodobała.

Znalazłam is the past tense of znaleźć (to find).

This form tells you two things:

• it is past tense: I found
• the speaker is female

A male speaker would say znalazłem.

Also, znaleźć is a perfective verb, so znalazłam suggests a completed result: I found it / I came across it, not I was finding it.

Polish often leaves out subject pronouns when they are clear from the verb form.

So:

• Znalazłam already means I found
• you do not need ja unless you want emphasis

If you said Ja znalazłam..., it would sound more emphatic, like I found it...

Mieszkanie (flat/apartment) is a neuter noun, so in the nominative singular it goes with to:

• ten for masculine
• ta for feminine
• to for neuter

So:

• to mieszkanie = this apartment/flat

Depending on context, to can also feel a bit like that in English, especially when referring to a specific place already known in the conversation.

Here przez means something like through, by means of, or via.

So:

• przez ogłoszenie = through an ad / via an advertisement

It describes the way the speaker found the apartment.

A learner may also hear other expressions in Polish, for example z ogłoszenia, which can also mean through/from an ad. In this sentence, przez ogłoszenie emphasizes the channel or medium.

After przez, Polish normally uses the accusative case.

So the phrase is:

• przez ogłoszenie

Here ogłoszenie looks the same as the nominative because many neuter singular nouns have the same form in the nominative and accusative.

So even though the form does not change visibly, the case is still accusative.

Because after w meaning in, Polish usually uses the locative case.

So:

• internet → w internecie = on the internet / in the internet

This is a very common pattern:

• w domu = in the house / at home
• w sklepie = in the shop
• w internecie = on the internet

Because jego refers back to mieszkanie, and mieszkanie is neuter.

In Polish:

• jego can mean his or its for a masculine or neuter possessor
• jej means her or its for a feminine possessor

So here:

• mieszkanie = neuter
• therefore jego lokalizacja = its location

Even though lokalizacja is feminine, that does not change the possessive pronoun here. The pronoun is about whose location it is: the apartment’s.

Polish often expresses to like with podobać się, which works differently from English.

Literally, it is closer to:

• X podoba się Y = X is pleasing to Y

So in this sentence:

• jego lokalizacja mi się spodobała
• literally: its location pleased me
• natural English: I liked its location

Why spodobała się and not lubiłam?

• lubić = to like in a more general or ongoing sense
• spodobać się = to come to like / to appeal to someone, often at a particular moment

With od razu (right away), spodobała się is especially natural: the location appealed to me immediately.

Mi means to me. It is the dative form of ja (I).

With podobać się, the person who likes something is expressed in the dative:

• Podoba mi się to mieszkanie = I like this apartment
• literally: This apartment is pleasing to me

So in your sentence:

• mi się spodobała = appealed to me / I liked it

Because the grammatical subject is lokalizacja, and lokalizacja is feminine.

In Polish past tense, the verb agrees with the subject in gender and number.

So:

• lokalizacja ... spodobała się
  not
• lokalizacja ... spodobał się

Compare:

• Dom mi się spodobał = The house appealed to me
• Książka mi się spodobała = The book appealed to me
• Mieszkanie mi się spodobało = The apartment appealed to me

Od razu means immediately, right away, or at once.

So:

• jego lokalizacja od razu mi się spodobała
• I liked its location right away

It is a very common Polish expression.

Examples:

• Zrobię to od razu = I’ll do it right away
• Od razu to zauważyłem = I noticed it immediately

Both can often translate as and, but they are not always used in the same way.

• i is a simple and
• a often links two ideas while also marking a slight contrast, shift, or separate comment

Here:

• Znalazłam to mieszkanie przez ogłoszenie w internecie, a jego lokalizacja...

This sounds natural because the speaker first says how they found the apartment, and then shifts to a new point: its location appealed to me immediately.

In English, a here is still usually translated as and.

The sentence is natural as written, but Polish word order is fairly flexible.

The original order is good because it flows clearly:

• first: I found this apartment through an ad online
• then: its location immediately appealed to me

You could move some parts for emphasis, for example:

• Od razu spodobała mi się jego lokalizacja
• Przez ogłoszenie w internecie znalazłam to mieszkanie

But changing the order changes emphasis or style. The original sentence is neutral and natural.