La lectura estimada aparece durante el periodo de facturación.

No. In this context, lectura means a meter reading or recorded reading, not reading text.

In utility or billing language, lectura often refers to the amount shown on a gas, electricity, or water meter. So la lectura estimada is an estimated meter reading.

In Spanish, adjectives usually come after the noun, especially when they are simply describing it in a neutral, factual way.

So:

• la lectura estimada = the estimated reading

Putting the adjective before the noun is much less common here and would sound more literary, marked, or unnatural in this type of administrative sentence.

Estimada is the feminine singular form of estimado, which comes from the verb estimar.

Here it works as an adjective meaning estimated.

It matches lectura, which is feminine singular:

• la lectura → feminine singular
• estimada → feminine singular

That agreement is required in Spanish.

Because it has to agree with lectura, which is a feminine noun.

Spanish adjectives normally agree in gender and number with the noun they describe:

• el consumo estimado = the estimated consumption
• la lectura estimada = the estimated reading
• las lecturas estimadas = the estimated readings

So the -a ending shows feminine singular agreement.

Aparece is the present indicative, third person singular, from the verb aparecer.

So it means:

• it appears
• it shows up

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

• La lectura estimada aparece...

Because the subject is singular:

• la lectura estimada = singular

So the verb must also be singular:

• la lectura estimada aparece

If the subject were plural, the verb would change:

• las lecturas estimadas aparecen

Because aparece means appears or is shown, which fits the idea that the reading is displayed during a certain period.

Compare:

• La lectura estimada aparece... = The estimated reading appears / is shown...
• La lectura estimada es... = The estimated reading is...

Using es would need more information after it, such as a description or value. On its own, aparece makes more sense in this sentence.

Durante means during.

It introduces a time period in which something happens:

• durante el periodo de facturación = during the billing period

This is more precise than just saying en in many cases, because durante clearly emphasizes that the action happens throughout or within that period of time.

Literally, it means period of billing or billing period.

The structure is:

• periodo = period
• de = of
• facturación = billing / invoicing

Spanish often uses noun + de + noun where English uses a compound noun:

• periodo de facturación = billing period
• factura de electricidad = electricity bill
• contador de agua = water meter

Because facturación is specifying what kind of periodo it is.

Spanish commonly links nouns with de to show this relationship:

• periodo de facturación = billing period
• número de cliente = customer number
• fecha de pago = payment date

Without de, the phrase would not be grammatical in standard Spanish.

Because Spanish often uses the definite article where English may or may not use the.

Here, el periodo de facturación refers to a specific type of period understood from the context: the billing period relevant to the account or bill.

So:

• durante el periodo de facturación = during the billing period

This sounds natural and standard in Spanish.

Yes. It is very common in administrative and utility contexts.

It usually means the company did not take an actual meter reading and instead calculated or estimated it.

You may also see related expressions such as:

• lectura real = actual reading
• lectura anterior = previous reading
• consumo estimado = estimated consumption

Yes, in many contexts that would also be possible:

• La lectura estimada se muestra durante el periodo de facturación.

That means The estimated reading is shown during the billing period.

However, aparece is perfectly natural if the idea is that it appears or shows up on the bill, screen, or account information. The exact choice depends on style and context, but both are understandable.

It is in a fairly formal, administrative, neutral style.

That is typical for billing, customer account, or utility-company language. It is not especially conversational, but it is very normal in official or technical contexts.