Ahora entiendo que algunas reglas familiares existen para protegernos, no como castigo.

In this sentence, reglas familiares means family rules or rules in the family, not familiar rules.

• reglas = rules
• familiares (as an adjective) = related to the family / belonging to the family

So reglas familiares = rules that come from or apply within the family (parents, home, etc.).

Be careful: familiar in English usually means well-known, but in Spanish familiar / familiares often means related to the family. It can also be a noun meaning relatives (mis familiares = my relatives), but here it is clearly an adjective modifying reglas.

Both word orders are grammatically correct:

• Ahora entiendo que algunas reglas familiares existen…
• Ahora entiendo que existen algunas reglas familiares…

The difference is a slight emphasis:

• algunas reglas familiares existen: puts more focus on the rules themselves.
• existen algunas reglas familiares: puts slightly more focus on the fact that they exist.

In everyday speech, que existen algunas reglas familiares is a bit more common-sounding, but the original sentence is perfectly natural and clear.

Yes, you could say:

• Ahora entiendo que hay algunas reglas familiares…

existen and hay are very close here:

• hay = there is / there are (more common, very neutral, used all the time)
• existen = literally exist (slightly more formal or explicit)

Nuance:

• hay algunas reglas familiares feels more conversational and is what most people would naturally say.
• algunas reglas familiares existen sounds a bit more explicit, like you’re stressing “these rules really do exist”.

Both are correct; hay is more frequent in speech.

Entender que normally takes the indicative because it expresses understanding or knowing a fact, not doubt or unreality.

• Ahora entiendo que algunas reglas familiares existen…
  = I now understand / realize that these rules exist (a fact you now accept).

You would use the subjunctive after verbs of doubt, emotion, wish, etc., for example:

• Dudo que existan reglas familiares así.
  I doubt that such family rules exist.

But entiendo que here is stating a belief in a real situation, so existen (indicative) is the correct and natural choice.

Both algunas and unas can mean some, but:

• algunas often suggests some (but not all), or a certain number of.
• unas is more like some as an indefinite article, often a bit looser or less specific.

Here:

• algunas reglas familiares hints that certain specific rules (not all family rules) exist for that purpose.

If you used unas reglas familiares, it would still be correct, but it can feel slightly more generic or less pointed. Algunas is a bit more natural when contrasting certain rules with other ones (e.g., some are to protect us, others may be for different reasons).

Spanish has fairly strict rules for pronoun placement with infinitives:

1. With an infinitive (proteger), object pronouns can:

   • attach to the end: protegernos
   • or go before the conjugated verb: existen para nos proteger is not standard.

2. After para

   • infinitive, the most natural is to attach the pronoun to the infinitive:
   • para protegernos ✅
   • para nos proteger ❌ (not natural/standard)
   • para proteger a nosotros ❌ (sounds wrong; pronoun form is off)

If you want to use a stressed pronoun, you would have to rephrase:

• para protegernos a nosotros (emphasis on us), but that’s heavier than necessary here.

So para protegernos is the normal, correct form.

nos is the first-person plural object pronoun: us.

• protegernos = to protect us

It includes the speaker and at least one other person, usually meaning the family members or children in this context.

If the speaker were only talking about themselves:

• protegerme = to protect me

If referring to them (some third group):

• protegerlos / protegerlas = to protect them
  (masculine/mixed = los, feminine = las)

In the sentence given, nos is correct because the idea is:
the family rules exist to protect us (the people in this family).

no como castigo literally means not as punishment.

The structure is:

• para protegernos, no como castigo
  = to protect us, not as a punishment.

The no is negating the phrase como castigo (as punishment), not the whole clause. It contrasts two possible purposes for the rules:

• Purpose A (real): to protect us
• Purpose B (rejected): as punishment

So it is like saying in English:
“…to protect us, not as punishment.”

Yes, you could say:

• …para protegernos, no como un castigo.

Both forms are fine:

• no como castigo = not as punishment (general idea)
• no como un castigo = not as a punishment (a specific instance or more countable sense)

In practice, the meaning here is essentially the same. No como castigo sounds a bit more abstract and general, and is very natural in this context.

Yes, you can move ahora around:

• Ahora entiendo que…
• Entiendo ahora que…

Both are correct. The differences are minimal:

• Ahora entiendo que… slightly emphasizes the time change: “Now I understand (I didn’t before).”
• Entiendo ahora que… can feel just a bit more focused on the act of understanding now, but in real-life usage they are nearly interchangeable.

Spanish allows adverbs like ahora to move quite freely, as long as the meaning stays clear.

Good observation. Familiar(es) can be both:

1. Adjective: related to the family

   • reglas familiares = family rules
   • ambiente familiar = family atmosphere

2. Noun: relatives, family members

   • Mis familiares viven en México. = My relatives live in Mexico.

In algunas reglas familiares, familiares is clearly an adjective because it modifies reglas (rules).

You do need que here. After verbs like entender, saber, decir, etc., when introducing a clause, Spanish requires que:

• Ahora entiendo que algunas reglas familiares existen… ✅

Without que, the sentence becomes ungrammatical:

• Ahora entiendo algunas reglas familiares existen… ❌

So treat entiendo que… like I understand that…; the que is the conjunction that.

Para is used to express purpose / goal:

• para protegernos = in order to protect us, for the purpose of protecting us

Por often expresses cause, reason, means, or exchange, but not intended purpose in this way.

Here the idea is clearly: the rules exist with the purpose of protecting us, so para is the correct preposition.

Spanish adjectives must agree in gender and number with the noun they describe.

• reglas is feminine plural: las reglas
• So the adjective must also be feminine plural: familiares

Forms:

• Singular: familiar (masc. and fem. the same)
• Plural: familiares

So:

• una regla familiar (one family rule)
• unas reglas familiares (some family rules)

Yes, that is another very natural way to express the contrast of purposes:

• Ahora entiendo que algunas reglas familiares existen no para castigarnos, sino para protegernos.

Here the pattern is:

• no para X, sino para Y = not in order to X, but rather in order to Y

The original sentence chooses to state only the real purpose in the main clause (para protegernos) and then add a short contrast (no como castigo). Using sino would make the contrast more explicit and balanced, but it slightly changes the structure from the original.