У этого платья длинный подол, и мама подняла его, чтобы не испачкать ткань.

Russian often expresses possession with the pattern у + genitive.

So:

• У этого платья = literally at this dress
• длинный подол = a long hem

The whole clause literally feels like At this dress, there is a long hem, but in natural English that becomes This dress has a long hem.

Russian does have иметь for to have, but in ordinary speech this у + genitive structure is much more common for simple possession.

Because the preposition у requires the genitive.

So:

• это платье = this dress in the nominative
• у этого платья = of / at this dress in the genitive-based possession structure

Both words change:

• этот → этого
• платье → платья

A useful thing to notice: платье is a neuter noun, so этого here is the genitive singular form used with neuter as well as masculine nouns.

Because подол is the thing being described, and it is in the nominative singular.

In this possession pattern:

• the possessor goes after у in the genitive
• the thing possessed stays in the nominative

So:

• подол is nominative singular
• длинный agrees with it in gender, number, and case

Since подол is masculine singular, the adjective is also длинный.

Подол is the hem or lower edge of a dress or skirt, especially the part hanging down near the bottom.

So in this sentence it refers to the long lower part of the dress that might drag on the ground and get dirty.

It is more specific than a general word like край (edge).

Because и is joining two separate clauses here.

Clause 1: У этого платья длинный подол

Clause 2: мама подняла его, чтобы не испачкать ткань

In Russian, when и connects two independent clauses, a comma is normally used before it.

There are two things happening here:

1. Past tense agrees with gender
   • поднял = masculine
   • подняла = feminine

Since мама refers to a woman, Russian uses подняла.

2. Aspect
   • поднять / подняла = perfective, a completed action
   • поднимать / поднимала = imperfective, an ongoing, repeated, or process-focused action

Here the sentence describes one completed action, so подняла is the natural choice.

Grammatically, его could refer to either:

• подол = masculine
• платье = neuter

The tricky part is that the accusative singular pronoun is его for both masculine inanimate and neuter nouns.

So the form itself does not tell you which noun is meant.

In context, many readers will understand его as referring to подол, because поднять подол is a very natural phrase: to lift the hem.

But the sentence is a little ambiguous on its own. If you wanted to make it completely clear, you could say:

• мама подняла подол
• мама подняла платье

Because его is the object form, while он and оно are subject forms.

Compare:

• Он длинный = It is long for a masculine noun
• Оно длинное = It is long for a neuter noun

But after a verb like подняла (lifted), Russian needs the object form:

• подняла его = lifted it

So его is used because it is the direct object of the verb.

This is a very common way to express purpose:

• чтобы = so that / in order to
• не испачкать = not to dirty

When the subject of the purpose clause is the same as the subject of the main clause, Russian often uses чтобы + infinitive.

Here, the understood subject is still мама:

• мама подняла его, чтобы не испачкать ткань
• Mother lifted it in order not to dirty the fabric

If Russian wanted to state a different subject more explicitly, it could use a finite verb instead.

Because испачкать is perfective, and that fits the meaning here.

• пачкать = to dirty, to make dirty, with an ongoing or repeated sense
• испачкать = to dirty, to get dirty once, with a clear result

After чтобы, Russian often uses the perfective infinitive when talking about preventing a single unwanted result:

• чтобы не испачкать ткань = so as not to get the fabric dirty

The focus is on avoiding the result, not on an ongoing process.

Ткань is the direct object of испачкать, so it is in the accusative case.

However, for this noun, the accusative singular looks the same as the nominative singular:

• nominative: ткань
• accusative: ткань

That is normal for many feminine nouns of this type.

Also, ткань literally means fabric or cloth. In this sentence it refers to the material of the dress. Russian chooses ткань to emphasize the fabric itself, not just the dress as an object.