Mały królik ma biały ogon i lubi siedzieć pod stołem.

Because królik is the subject of the sentence, so it stays in the nominative case.

• mały królik = the small rabbit
• This is the thing doing the action.

You would see królika in other roles, for example as a direct object:

• Widzę królika. = I see a rabbit.

They agree with the nouns they describe in gender, number, and case.

Both królik and ogon are:

• masculine
• singular
• in the forms needed here

So the adjectives also take masculine singular endings:

• mały królik
• biały ogon

This is called adjective agreement, and it is a very important feature of Polish.

Because the verb mieć (to have) normally takes a direct object in the accusative.

Here, ogon is a masculine inanimate noun, and in the singular its accusative form is the same as the nominative:

• nominative: ogon
• accusative: ogon

The adjective follows that pattern too:

• nominative: biały
• accusative: biały

So:

• ma biały ogon = has a white tail

If the noun were masculine animate, the accusative would usually look different:

• Widzę małego psa. = I see a small dog

Because pod can take different cases depending on the meaning.

Here it means location: the rabbit is under the table, in a fixed place.
With a location meaning, pod takes the instrumental case.

So:

• stół = table (dictionary form)
• pod stołem = under the table

If there were movement to a position under the table, Polish would often use the accusative:

• wchodzi pod stół = it goes under the table

So the contrast is roughly:

• pod stołem = location
• pod stół = movement/direction

Because after pod in a location meaning, the noun must be in the instrumental case.

The noun stół changes like this:

• nominative: stół
• instrumental: stołem

So:

• pod stołem = under the table

This is just a normal case ending for this noun.

After lubić (to like), Polish often uses an infinitive to say that someone likes doing something.

So:

• lubi siedzieć = likes to sit / likes sitting

This works much like English:

• lubi czytać = likes to read
• lubi spać = likes sleeping / likes to sleep

Because siedzieć means to be sitting / to sit as a state, while siadać means to sit down as an action of getting into that position.

Here the sentence describes what the rabbit likes in general:

• lubi siedzieć pod stołem = it likes sitting under the table

That is why siedzieć is the natural choice.

Compare:

• siedzieć = to be sitting
• siadać = to sit down, to start sitting

Because lubić is the infinitive (to like), while lubi is the conjugated form meaning he/she/it likes.

The subject is mały królik, which is third person singular, so the verb must match it:

• ja lubię = I like
• ty lubisz = you like
• on/ona/ono lubi = he/she/it likes

So:

• mały królik lubi = the small rabbit likes

Polish usually does not use articles like English a/an/the.

So królik can mean:

• a rabbit
• the rabbit

And ogon can mean:

• a tail
• the tail

The exact meaning depends on context.
That is completely normal in Polish.

Yes, Polish word order is more flexible than English because case endings show grammatical roles.

The basic version:

• Mały królik ma biały ogon i lubi siedzieć pod stołem.

But other orders are possible for emphasis, for example:

• Biały ogon ma mały królik...
• Pod stołem lubi siedzieć mały królik.

These alternatives may sound more marked or emphatic.
The original sentence is the most neutral and natural for a simple statement.

I means and.

It connects two parts:

• ma biały ogon = has a white tail
• lubi siedzieć pod stołem = likes to sit under the table

So the sentence has one subject, mały królik, and two linked statements about it.

A rough English-friendly pronunciation is KROO-leek, but that is only approximate.

A few helpful points:

• ó sounds like Polish u, roughly like oo in food
• ł sounds like English w
• stress is usually on the second-to-last syllable, so KRÓ-lik

So królik sounds approximately like KROO-leek, with the first syllable stressed.

A rough approximation is STO-wem.

Helpful points:

• ł is pronounced like English w
• ę is a nasal vowel, but before some consonants and in normal speech it often sounds closer to em/en

So stołem is often heard approximately as STO-wem.

It can often mean both, depending on context.

• mały królik can be understood as a small rabbit
• In some contexts, it may sound like a little rabbit

Polish mały covers a lot of the same ground as English small/little, though the exact tone depends on the situation.