La señal es débil.

Because señal is a countable noun and in normal Spanish sentences it often takes an article, especially when you are talking about a specific signal or the signal in general in that situation.

So La señal es débil sounds natural for The signal is weak.

In English, we sometimes drop articles more easily, but Spanish usually keeps them:

• La señal es débil.
• La conexión es lenta.
• El internet va mal.

Dropping la here would usually sound incomplete or unnatural.

Because grammatical gender in Spanish is not always predictable from the ending.

Many feminine nouns do end in -a, but some do not. Señal is simply a feminine noun, so it uses:

• la señal
• una señal

You just have to learn its gender with the word.

Other feminine nouns that do not end in -a include:

• la ciudad
• la pared
• la razón

So the important thing is to memorize señal as la señal.

It is pronounced approximately like seh-NYAL.

A few key points:

• se- sounds like seh
• ñ is like the ny sound in canyon
• -al sounds like ahl

So:

• señal ≈ seh-NYAL

The stress falls on the last syllable:

• se-ÑAL

The letter ñ is a separate letter in Spanish, not just an n with a mark on it.

It represents a sound like:

• ny in canyon
• gn in some pronunciations of lasagna

So:

• n = normal n
• ñ = ny

Compare:

• ano and año
• pena and peña

In señal, the ñ is essential. Without it, it would be a different spelling and not the same word.

This is a very common question because both ser and estar can mean to be.

Here, es comes from ser, and La señal es débil is the normal way to say The signal is weak.

Why? Because débil is being used as a general quality or characteristic of the signal in that context.

• es débil = is weak

Using está débil is generally not the standard choice here. For things like signal strength, Spanish normally uses ser:

• La señal es buena.
• La señal es mala.
• La señal es débil.

This is one of those combinations that is best learned as a natural expression.

In your sentence, débil comes after es, so it is not directly modifying the noun inside the noun phrase. It is acting as an adjective after the verb, describing the subject:

• La señal = the subject
• es = is
• débil = weak

This is called a predicate adjective.

In English, we do the same thing:

• The signal is weak.

If you wanted the adjective directly next to the noun, you could say:

• la señal débil = the weak signal

But your sentence is structured as:

• The signal is weak, not the weak signal

Because some Spanish adjectives have the same form for masculine and feminine singular.

So:

• el sonido es débil
• la señal es débil

Both use débil.

What does change is the plural:

• la señal es débil
• las señales son débiles

So débil works like this:

• masculine singular: débil
• feminine singular: débil
• masculine plural: débiles
• feminine plural: débiles

The accent mark shows where the stress goes:

• DÉ-bil

Without the accent mark, Spanish stress rules would suggest a different pronunciation. The written accent tells you that the first syllable is stressed.

This accent mark is part of the correct spelling:

• débil = correct
• debil = incorrect

It helps both with pronunciation and spelling.

You would change all the parts that need to agree:

• La señal es débil. = The signal is weak.
• Las señales son débiles. = The signals are weak.

Changes:

• la → las
• señal → señales
• es → son
• débil → débiles

This is a good example of agreement in Spanish.

For a question:

• ¿La señal es débil? = Is the signal weak?

Spanish often uses the same word order as a statement, and the question marks show that it is a question.

For a negative:

• La señal no es débil. = The signal is not weak.

The word no goes before the verb:

• no es

So:

• statement: La señal es débil.
• question: ¿La señal es débil?
• negative: La señal no es débil.

Yes. Señal is a broad word and can refer to different kinds of signals depending on context, such as:

• phone signal
• TV signal
• radio signal
• Wi-Fi or reception signal
• a sign or signal in a more general sense

So La señal es débil could mean:

• the phone signal is weak
• the TV signal is weak
• the reception is weak

The exact meaning depends on the situation. In everyday use, people often understand it from context without needing to specify more.