Jeśli chodzi o gramatykę, najbardziej lubię krótkie przykłady z podręcznika.

No—the literal word-for-word breakdown can look strange in English, but as a whole, jeśli chodzi o is a fixed expression meaning:

• as for
• when it comes to
• regarding
• speaking of

So in this sentence, Jeśli chodzi o gramatykę means When it comes to grammar or As for grammar.

Even though jeśli often means if, in this expression you should learn the whole phrase together rather than translating each word separately.

Because o in the phrase jeśli chodzi o requires the accusative case.

The dictionary form is gramatyka.
In the accusative singular, it becomes gramatykę.

So:

• gramatyka = grammar
• o gramatykę = about grammar / as for grammar

This is one of those places where you should learn the phrase with its case pattern:

• jeśli chodzi o + accusative

For example:

• Jeśli chodzi o pracę... = As for work...
• Jeśli chodzi o dzieci... = As for the children...

Because Jeśli chodzi o gramatykę is an introductory phrase. In Polish, such introductory elements are often separated by a comma from the main clause.

So the structure is:

• Jeśli chodzi o gramatykę, = introductory topic phrase
• najbardziej lubię krótkie przykłady z podręcznika. = main statement

This is very similar to English punctuation in sentences like:

• As for grammar, ...
• When it comes to grammar, ...

Here najbardziej means most.

It comes from bardzo = very, much, a lot.
Then:

• bardziej = more
• najbardziej = most

So:

• lubię = I like
• najbardziej lubię = I like the most

In this sentence, it tells you what the speaker likes most within the topic being discussed.

Yes, both are possible, but the emphasis changes slightly.

• najbardziej lubię krótkie przykłady z podręcznika = neutral, natural
• lubię najbardziej krótkie przykłady z podręcznika = also possible, but a bit more marked
• krótkie przykłady z podręcznika lubię najbardziej = stronger emphasis on short examples from the textbook

Polish word order is more flexible than English, but that does not mean all word orders feel equally natural in every context. In this sentence, najbardziej lubię is a very standard and smooth choice.

Because krótkie przykłady is the accusative plural form, and for non-masculine-personal nouns, the accusative plural is the same as the nominative plural.

The noun here is:

• przykład = example

Plural nominative:

• przykłady = examples

Accusative plural:

• also przykłady

The adjective must agree with the noun:

• krótkie przykłady = short examples

So after lubię (I like), the direct object goes into the accusative:

• Lubię krótkie przykłady.

Why not krótkich przykładów?
That form is genitive plural, not accusative plural, so it would not fit here.

Because lubić takes a direct object, and direct objects in Polish are usually in the accusative.

So:

• lubić coś = to like something
• lubię książkę = I like the book
• lubię filmy = I like films
• lubię krótkie przykłady = I like short examples

This is one of the most important basic verb patterns to remember:

• lubić + accusative

Podręcznika is genitive singular.

The dictionary form is:

• podręcznik = textbook

After z meaning from/out of, Polish uses the genitive:

• z podręcznika = from the textbook

So the phrase means that the examples come from the textbook.

Be careful: z can take different cases depending on meaning.

• z + genitive = from, out of
• z + instrumental = with

Here it is clearly from the textbook, so it is genitive:

• z podręcznika

No, the meaning is different.

• z podręcznika = from the textbook
• w podręczniku = in the textbook

So:

• krótkie przykłady z podręcznika = short examples from the textbook
• krótkie przykłady w podręczniku = short examples in the textbook

Both can make sense, but they are not identical.
In your sentence, z podręcznika suggests the examples are taken from that textbook as a source.

Because Polish has no articles—no separate words for a, an, or the.

So Polish simply says:

• podręcznik = textbook / a textbook / the textbook
• przykłady = examples / the examples

The exact meaning depends on context.

In English, you must choose between a textbook and the textbook, but in Polish that distinction is usually understood from the situation or from other words in the sentence.

The sentence can be divided like this:

• Jeśli chodzi o gramatykę, = topic frame / introductory phrase
• najbardziej lubię = main verb phrase
• krótkie przykłady = direct object
• z podręcznika = modifier of examples

So the full structure is:

When it comes to grammar, I like short examples from the textbook most.

Or more naturally in English:

When it comes to grammar, I like short textbook examples best.

Yes, it is grammatically possible, but it is less neutral than the original.

The original:

• Jeśli chodzi o gramatykę, najbardziej lubię krótkie przykłady z podręcznika.

is a very natural, standard way to say it.

Your alternative:

• Jeśli chodzi o gramatykę, lubię najbardziej krótkie przykłady z podręcznika.

is understandable, but sounds a bit more marked in rhythm and emphasis.

When learning Polish, it is usually best to keep the original order unless you specifically want to shift emphasis.

Here are the main forms:

• jeśli = if
• chodzić = to go, to be about
• gramatyka = grammar
• najbardziej = most
• lubić = to like
• krótki = short
• przykład = example
• podręcznik = textbook

And the forms used in the sentence are:

• chodzi = 3rd person singular present
• gramatykę = accusative singular
• lubię = 1st person singular present
• krótkie = plural adjective agreeing with przykłady
• przykłady = accusative plural
• podręcznika = genitive singular

Yes, it is the same verb family, but here it is used idiomatically.

• chodzić can mean to go/walk repeatedly
• but in expressions like chodzi o, it means to be about, to concern

Examples:

• O co chodzi? = What is it about? / What’s going on?
• Chodzi o pieniądze. = It’s about money.
• Jeśli chodzi o gramatykę... = When it comes to grammar...

So this is a very common case where a verb has a meaning in a fixed expression that is different from its most basic physical meaning.