Meine Schwester möchte auch einen Kaffee trinken.

In German, all nouns are capitalized, not just proper names.

So in this sentence:

• meine = my
• Schwester = sister

Because Schwester is a noun, it must be written with a capital S.

Examples:

• meine Mutter
• der Kaffee
• ein Buch

This is one of the most noticeable spelling differences between German and English.

Because Schwester is a feminine noun, the possessive word has to match it.

German possessives change their endings depending on:

• gender
• case
• number

Here, Schwester is:

• feminine
• singular
• nominative (the subject of the sentence)

So the correct form is meine.

Compare:

• mein Bruder = my brother
• meine Schwester = my sister
• mein Kind = my child

So the -e ending shows agreement with a feminine singular noun in the nominative.

Because Kaffee is the direct object of the verb trinken, so it is in the accusative case.

Kaffee is a masculine noun:

• nominative: ein Kaffee
• accusative: einen Kaffee

In this sentence:

• Meine Schwester = subject
• möchte ... trinken = wants/would like to drink
• einen Kaffee = what she wants to drink

So the masculine article changes from ein to einen in the accusative.

Compare:

• Ein Kaffee ist heiß. → subject, nominative
• Ich trinke einen Kaffee. → object, accusative

Möchte usually means would like.

So Meine Schwester möchte auch einen Kaffee trinken is more like:

• My sister would also like to drink a coffee rather than a strong wants.

This is important because möchte is softer and more polite than will.

Compare:

• Ich will Kaffee trinken. = I want to drink coffee.
  This can sound quite strong or blunt.
• Ich möchte Kaffee trinken. = I would like to drink coffee.
  This sounds more natural and polite in many situations.

So möchte is extremely common in everyday German.

Not exactly. Möchte is historically a special form of mögen and is usually treated as a polite form meaning would like.

Learners often meet:

• ich möchte
• du möchtest
• er/sie/es möchte
• wir möchten
• ihr möchtet
• sie/Sie möchten

Even though it comes from mögen, in everyday use it often functions almost like its own verb meaning would like.

So in practice, it is best to learn möchte as the standard way to say would like.

Because German often sends the main infinitive to the end when there is a finite verb like möchte earlier in the sentence.

In this sentence:

• möchte is the conjugated verb in second position
• trinken is the infinitive and goes to the end

Pattern:

• subject + conjugated verb + other elements + infinitive

Examples:

• Ich möchte heute nach Hause gehen.
• Wir möchten ein Eis essen.
• Sie möchte Deutsch lernen.

This is one of the most important German word-order patterns to get used to.

Because möchte takes a bare infinitive, just like modal verbs do.

So you say:

• Ich möchte Kaffee trinken. not
• Ich möchte Kaffee zu trinken.

After verbs like können, müssen, wollen, and also möchte, the second verb usually appears in the infinitive without zu.

Examples:

• Ich kann schwimmen.
• Er will gehen.
• Wir möchten essen.

So möchte ... trinken is completely normal.

Auch means also or too.

In this sentence, it suggests that the sister is being added to a group of people who want coffee, or that coffee is an additional thing she wants.

Most naturally here, it means:

• My sister would also like to drink a coffee or
• My sister, too, would like a coffee

Exactly what auch emphasizes depends on context.

For example:

• Auch meine Schwester möchte einen Kaffee trinken.
  = My sister too would like a coffee.
• Meine Schwester möchte auch einen Kaffee trinken.
  = my sister would also like a coffee

The sentence you have is very natural and common.

Yes, German word order is flexible, but the conjugated verb usually stays in second position in a main clause.

Your sentence:

• Meine Schwester möchte auch einen Kaffee trinken.

Other possible versions:

• Auch meine Schwester möchte einen Kaffee trinken.
  This emphasizes my sister too.
• Einen Kaffee möchte meine Schwester auch trinken.
  This is possible, but more marked and less neutral.

The basic rule is:

• one element comes first
• the conjugated verb comes second

So if you move something to the front, the verb still stays second.

Yes, both are possible, but they mean slightly different things.

• einen Kaffee trinken = drink a coffee, one coffee, a cup of coffee
• Kaffee trinken = drink coffee, coffee in general

So:

• Meine Schwester möchte einen Kaffee trinken.
  focuses on one coffee
• Meine Schwester möchte Kaffee trinken.
  is more general

This is similar to English:

• to drink a coffee
• to drink coffee

In everyday speech, einen Kaffee is very common when talking about ordering or having a cup of coffee.

Yes, very much so.

German often uses trinken with drinks in exactly this way:

• einen Kaffee trinken
• ein Bier trinken
• einen Tee trinken

It is the normal way to say someone is having a coffee, beer, tea, etc.

In English, have a coffee is often more common than drink a coffee, but in German einen Kaffee trinken is completely standard.

Meine Schwester is in the nominative case because it is the subject of the sentence.

You can find the subject by asking: who is doing the action?

Who would like to drink a coffee?

• Meine Schwester

So:

• meine Schwester = nominative
• einen Kaffee = accusative

This sentence is a good simple example of:

• subject in nominative
• direct object in accusative

Yes.

It can refer to:

• your actual biological sister
• your stepsister, depending on context
• sometimes even a figurative sister in religious or social contexts, though that is not the default meaning

In normal everyday use, meine Schwester simply means my sister.

German does not require any extra word like older or younger unless you want to specify:

• meine ältere Schwester = my older sister
• meine jüngere Schwester = my younger sister

The main change would be in the possessive and the verb form.

For example:

• Meine Schwestern möchten auch einen Kaffee trinken.
  = My sisters would also like to drink a coffee.

Changes:

• Schwester → Schwestern for plural
• möchte → möchten to match the plural subject

Notice that meine stays the same here:

• meine Schwester
• meine Schwestern

So German agreement affects the verb, and sometimes the noun form, but not always every word in the phrase.