Mi hermano tiene calor y abre la ventana.

In Spanish, the normal way to say a person feels hot is tener calor — literally, to have heat.

So:

• Mi hermano tiene calor = My brother is hot / feels hot

If you say está caliente about a person, it usually does not mean simply that they feel warm. It can sound strange, sexual, or mean something very different depending on context. For people, tener calor is the safe, natural expression in Latin America and elsewhere in the Spanish-speaking world.

Because tener calor is a fixed expression in Spanish, just like:

• tener hambre = to be hungry
• tener sed = to be thirsty
• tener frío = to be cold
• tener sueño = to be sleepy

In these expressions, Spanish normally does not use an article.

So you say:

• Tiene calor
• not Tiene el calor

Using el here would sound unnatural in this meaning.

Mi means my, and it does not change for masculine or feminine singular nouns.

So:

• mi hermano = my brother
• mi hermana = my sister

For plural nouns, it becomes mis:

• mis hermanos = my brothers / my siblings
• mis hermanas = my sisters

So mi is correct because hermano is singular.

Spanish often leaves out subject pronouns when they are already clear from the verb or the context. This is very common in Latin American Spanish too.

So instead of saying:

• Mi hermano tiene calor y él abre la ventana

Spanish usually just says:

• Mi hermano tiene calor y abre la ventana

The subject mi hermano is understood to apply to both verbs: tiene and abre.

Including él is possible, but it usually adds emphasis, contrast, or clarification.

Yes. In this sentence, mi hermano is the subject of both verbs:

• mi hermano tiene calor
• (mi hermano) abre la ventana

The second subject is omitted because it is understood. This is a very common structure in Spanish when the same subject does two actions connected by y.

Abre is the third-person singular present tense of the verb abrir (to open).

Conjugation of abrir in the present:

• yo abro
• tú abres
• él/ella/usted abre
• nosotros/nosotras abrimos
• ustedes abren
• ellos/ellas abren

Since mi hermano = he, the correct form is abre.

The Spanish present tense can mean either:

1. something happening now, or
2. something habitual / generally true

So Mi hermano tiene calor y abre la ventana could mean:

• My brother feels hot and opens the window
• or, depending on context, When my brother feels hot, he opens the window

Without more context, the sentence is usually understood as a normal present-time statement. Context tells you whether it is happening right now or describes a usual action.

If you want to emphasize right now, Spanish often uses:

• Mi hermano tiene calor y está abriendo la ventana
  = My brother is opening the window

But in many cases, simple present is perfectly natural.

La ventana means the window, referring to a specific, understood window.

Spanish uses the definite article here because the speaker and listener are assumed to know which window is being talked about — probably the window in the room they are in or the one relevant to the situation.

If you said una ventana, it would mean a window, any window, or a window not yet identified.

So:

• abre la ventana = opens the window
• abre una ventana = opens a window

Y means and. It connects the two parts of the sentence:

• Mi hermano tiene calor
• abre la ventana

So the whole sentence shows two linked actions or ideas:

1. my brother feels hot
2. he opens the window

It works just like and in English.

Hermano means brother and is masculine.
Hermana means sister and is feminine.

So:

• mi hermano = my brother
• mi hermana = my sister

The ending -o often marks masculine nouns, and -a often marks feminine nouns, though not always. In this sentence, hermano is used because the person is male.

In Spanish, the letter h is usually silent.

So hermano is pronounced roughly like er-MAH-no.

This is just part of Spanish spelling. Many words keep the written h even though it is not pronounced, such as:

• hola
• hacer
• hijo
• hermano

So you write hermano, but you do not pronounce the h sound.