Mi hermana tarda poco en teclear un correo largo.

Tardar en + infinitive means to take time to do something.

So:

• tarda en teclear = she takes time to type
• tarda poco en teclear = she doesn’t take long to type / she takes little time to type

In this sentence, poco means not much / little, so the idea is that your sister types a long email quickly.

Because tarda is the verb conjugated for mi hermana.

The verb is tardar.
Its present tense forms include:

• yo tardo
• tú tardas
• él / ella tarda
• nosotros tardamos
• vosotros tardáis
• ellos / ellas tardan

Since mi hermana = she, you use tarda.

Because the normal structure is:

tardar en + infinitive

Examples:

• Tardo mucho en terminar. = I take a long time to finish.
• Tardas poco en vestirte. = You don’t take long to get dressed.
• Mi hermana tarda poco en teclear un correo largo.

So the en is required by the verb pattern here.

Teclear specifically means to type or to key in something, usually on a keyboard.

Escribir means to write, and it can be broader:

• by hand
• on a computer
• in a general sense

So:

• teclear un correo = to type an email
• escribir un correo = to write an email

Both can work, but teclear focuses on the physical act of typing.

It can mean either, depending on context.

In modern everyday Spanish, especially in contexts involving computers or typing, un correo often means an email.

So in this sentence, because we have teclear and un correo largo, it most naturally means a long email.

If someone wanted to be more explicit, they could say:

• un correo electrónico = an email

Because correo is a masculine noun:

• el correo
• un correo

That is why the adjective also appears in masculine form:

• un correo largo

In Spanish, adjectives often come after the noun.

So:

• un correo largo = a long email

That is the most neutral, standard order.

You may sometimes see adjectives before nouns, but that often adds a special stylistic or subjective nuance. Here, correo largo is the normal choice.

In Spanish, possessive words like mi, tu, su, nuestro usually replace the article.

So you say:

• mi hermana
• tu hermano
• su madre

Not usually:

• la mi hermana ❌

English works similarly:

• my sister, not the my sister

Here, poco is functioning like an adverbial expression modifying tarda.

It tells you how much time she takes:

• tarda poco = she takes little time
• tarda mucho = she takes a long time

So in this sentence, poco is not describing a noun; it is describing the amount of time involved in the action.

No, that would not be standard Spanish.

With tardar in this meaning, you normally need:

tardar en + infinitive

So the correct version is:

• Mi hermana tarda poco en teclear un correo largo.

Without en, it sounds incomplete or ungrammatical.

It normally means she takes little time to complete the action.

So the focus is on the duration of typing the long email, not just on starting it.

In other words, the sentence suggests that typing a long email does not take her long.

Yes, it can. In Spain, teclear is understood and natural for typing.

That said, many speakers might also simply say:

• escribir un correo largo

because in real life writing an email often implies typing it.

So teclear is correct and understandable, but it is a bit more specific than escribir.

No, not with tardar in this structure.

You say:

• tardar en hacer algo

not

• tardar para hacer algo ❌

Para usually expresses purpose, while en is part of the fixed pattern with tardar.

Because there is no direct object referring to a specific person.

The direct object here is:

• un correo largo

That is a thing, not a person, so no personal a is needed.

The subject is mi hermana, and subjects do not take the personal a.

Yes. Since mi hermana is she, you could say:

• Ella tarda poco en teclear un correo largo.

Spanish often drops subject pronouns when the subject is clear from the verb:

• Tarda poco en teclear un correo largo.

That is also perfectly normal if the context already makes it clear who you are talking about.