La alerta de saldo bajo funciona bien.

In standard Spanish, alerta is usually treated as a feminine noun when it means an alert or a warning, so la alerta is the safest form to learn.

You may hear other uses in some places or contexts, but for general Latin American Spanish, la alerta is the normal choice.

Also, alerta can be used in other ways, such as estar alerta = to be alert, where it is not functioning as a noun.

Here, saldo means balance or available credit.

In Latin American Spanish, it can refer to things like:

• a bank account balance
• prepaid phone credit
• money left on a card or account
• available funds in an app or service

So saldo bajo means low balance or low credit, depending on the context.

Spanish often uses de to connect nouns where English might simply stack them together.

So:

• alerta de saldo bajo literally means something like alert of low balance
• in natural English, that becomes low-balance alert

This is a very common Spanish pattern. For example:

• tarjeta de crédito = credit card
• mensaje de texto = text message
• centro de ayuda = help center

Because bajo describes saldo, not alerta.

The phrase breaks down like this:

• la alerta = the alert
• de saldo bajo = of low balance

Since saldo is masculine singular, the adjective must also be masculine singular:

• saldo bajo

If the noun were feminine, the adjective would change:

• batería baja = low battery

In Spanish, adjectives often come after the noun.

So English says:

• low balance

But Spanish usually says:

• saldo bajo

That word order is normal in Spanish. Putting bajo before saldo here would sound unusual.

Funciona is the third-person singular present indicative form of funcionar, which means to function or to work.

The subject is la alerta, which is singular, so the verb is singular too:

• La alerta funciona

In context, this can mean:

• The alert works well
• The alert is working well

Spanish present tense can often cover both ideas.

Because funcionar is the normal verb for saying that a system, feature, device, or service works.

So:

• La alerta funciona bien = the alert works well

Compare:

• La alerta es buena = the alert is good
• La alerta está bien = the alert is fine / okay

Those are possible sentences, but they do not express the idea of working properly as clearly as funciona bien.

Because bien is an adverb, and it modifies the verb funciona.

• funciona bien = works well

Buena is an adjective, so it describes a noun, not a verb.

Compare:

• La alerta funciona bien = The alert works well.
• La alerta es buena = The alert is good.

That is an important Spanish pattern:

• verbs are often modified by bien
• nouns are described by adjectives like bueno / buena

Usually no in a normal sentence.

In Spanish, a singular count noun used as the subject of a sentence usually needs an article:

• La alerta de saldo bajo funciona bien.

Without la, it sounds more like:

• a title
• a heading
• a menu label
• the name of a feature

So:

• as a full sentence: La alerta de saldo bajo funciona bien.
• as a label or feature name: Alerta de saldo bajo