Я возьму другой зонтик, потому что этот мокрый.

Возьму means I will take or I'll take.

It is the 1st person singular future form of the verb взять (to take, perfective).

Russian perfective verbs do not have a true present tense. Their present-looking endings are used for the simple future instead. So:

• я возьму = I will take
• not I take in this context

That fits the sentence, because the speaker is talking about what they are going to do next.

This is a very common learner question, because взять is an irregular verb in its future forms.

Its forms are:

• я возьму
• ты возьмёшь
• он/она возьмёт
• мы возьмём
• вы возьмёте
• они возьмут

So yes, the stem changes, and this is something you mostly have to memorize.

This kind of change is normal in some very common Russian verbs.

It actually is functioning as the direct object, so it is in the accusative case.

However, зонтик is:

• masculine
• singular
• inanimate

For masculine inanimate nouns, the accusative singular looks exactly like the nominative singular.

So:

• nominative: зонтик
• accusative: зонтик

Even though the form looks the same, the case is accusative because it is the thing being taken.

In this sentence, другой can feel like both another and different, and that is normal.

The idea is:

• I’ll take another umbrella
• or more literally, I’ll take a different umbrella

Because the reason is that this one is wet, different is probably the clearest interpretation.

Also, другой agrees with зонтик:

• masculine
• singular
• accusative inanimate

But again, that form looks the same as nominative, so it stays другой.

Because этот agrees with the noun зонтик, which is masculine singular.

Compare:

• этот зонтик = this umbrella or this one
• эта книга = this book (feminine)
• это окно = this window (neuter)

In the sentence, the noun is omitted in the second part, but it is still understood:

• этот (зонтик) мокрый

So этот means this one, with зонтик understood.

Because in Russian, the verb to be is usually omitted in the present tense.

So:

• этот мокрый literally looks like this wet
• but it means this one is wet

This is completely normal Russian grammar.

Compare:

• Он дома. = He is at home.
• Книга интересная. = The book is interesting.
• Этот мокрый. = This one is wet.

If the sentence were in the past or future, Russian would use forms of быть:

• Этот был мокрый. = This one was wet.
• Этот будет мокрый. = This one will be wet.

Мокрый means wet, and it is in the masculine singular form because it agrees with the understood noun зонтик.

So the hidden structure is really:

• этот зонтик мокрый

Since зонтик is masculine, the adjective must also be masculine:

• мокрый for masculine
• мокрая for feminine
• мокрое for neuter
• мокрые for plural

Yes, absolutely.

Both are correct:

• этот мокрый
• этот зонтик мокрый

The version without зонтик sounds natural because the noun is already clear from the context. Russian often leaves out repeated words when they are obvious.

So:

• Я возьму другой зонтик, потому что этот мокрый.
  = natural, concise
• Я возьму другой зонтик, потому что этот зонтик мокрый.
  = also correct, but more repetitive

Because потому что means because and introduces a subordinate clause.

Russian normally puts a comma before this kind of clause:

• Я возьму другой зонтик, потому что этот мокрый.

This is standard punctuation.

The sentence is basically:

• main clause: Я возьму другой зонтик
• subordinate reason clause: потому что этот мокрый

Yes, Russian word order is fairly flexible, although some versions sound more neutral than others.

The given sentence:

• Я возьму другой зонтик, потому что этот мокрый.

is a very natural, neutral way to say it.

You could also say:

• Потому что этот мокрый, я возьму другой зонтик.

That puts more emphasis on the reason first.

Russian word order often changes for:

• emphasis
• contrast
• style
• information flow

But the original order is probably the one most learners should use first.

They are very close.

• зонт = umbrella
• зонтик = literally a diminutive form, something like little umbrella

But in modern everyday Russian, зонтик is extremely common and often just means umbrella in a normal, neutral way.

So in many contexts, both are possible:

• Я возьму другой зонт.
• Я возьму другой зонтик.

The difference is usually small. Зонтик can sound a bit more everyday or a bit softer, while зонт can sound slightly more plain or technical, depending on context.