Sie schämt sich nach dem Streit.

Yes. Sie can mean:

• she
• they
• formal you

At the start of a sentence, Sie is always capitalized, so capitalization alone does not tell you which one it is.

Only context tells you the meaning. In this sentence, if the meaning shown to the learner is she is ashamed after the argument, then Sie means she.

Because sich schämen is a reflexive verb in German.

The basic expression is:

• sich schämen = to be ashamed

So German does not usually say this with just schämen by itself. It normally needs a reflexive pronoun:

• ich schäme mich
• du schämst dich
• sie schämt sich

Even though it looks literally like she shames herself, that is not how it functions idiomatically. It simply means she is ashamed or she feels ashamed.

Because the verb sich schämen takes a reflexive pronoun, and for third person the accusative reflexive pronoun is sich.

So:

• ich schäme mich
• du schämst dich
• er/sie/es schämt sich
• wir schämen uns
• ihr schämt euch
• sie/Sie schämen sich

Here the subject is third person singular (sie = she), so the correct reflexive pronoun is sich.

schämt is the 3rd person singular present tense form of sich schämen.

Infinitive:

• sich schämen

Present tense:

• ich schäme mich
• du schämst dich
• sie schämt sich

So schämt matches the subject Sie meaning she.

Because nach takes the dative case here.

• nach = after in this sentence
• der Streit = the argument / quarrel in the nominative
• dative masculine of der Streit is dem Streit

So:

• nach dem Streit = after the argument

This is a very common pattern:

• nach dem Essen = after the meal
• nach der Arbeit = after work
• nach dem Unterricht = after class

Because Streit is a noun, and all nouns are capitalized in German.

So:

• der Streit = the argument
• die Scham = shame
• das Haus = the house

This is one of the most noticeable spelling rules in German.

It is normal German main-clause word order.

The pattern is:

• Sie = subject
• schämt = finite verb
• sich = reflexive pronoun
• nach dem Streit = prepositional phrase

German main clauses usually put the finite verb in second position. That is exactly what happens here:

• Sie schämt sich nach dem Streit.

You can also move the time phrase to the front:

• Nach dem Streit schämt sie sich.

That still means the same thing, but now schämt stays in second position.

Yes, it is present tense.

German often uses a verb where English uses to be + adjective.

So:

• Sie schämt sich literally looks verbal
• natural English may be She is ashamed or She feels ashamed

That is completely normal. German sich schämen is the standard way to express this idea.

Here nach is mainly temporal: after the argument.

It tells you when she feels ashamed.

It does not directly mean because of. If you wanted to focus more on cause, German might use something like:

• wegen des Streits = because of the argument

So there is a small difference:

• nach dem Streit = after the argument
• wegen des Streits = because of the argument

Sometimes both ideas are true in context, but the grammar here expresses after, not explicitly because of.

A rough pronunciation guide is:

• sch sounds like English sh
• ä is somewhat like the vowel in bed, though not exactly the same
• schämt is roughly shemt
• sich is not pronounced like English sitch; the ch is the soft German sound heard in ich

Very roughly:

• Sie schämt sich ≈ zee shemt zikh

That is only an approximation, but it can help as a starting point.