Por la noche, enciendo la lámpara que está sobre la mesilla y leo un rato.

In Spanish, por la noche is the normal way to mean at night / in the evening as a time expression.

• por la mañana = in the morning
• por la tarde = in the afternoon/evening
• por la noche = at night

En la noche does exist, but it is much less common in Spain for this general meaning. It usually sounds more specific or literary, depending on context.

So here, por la noche is the natural everyday choice.

Enciendo is the 1st person singular present indicative of encender.

So it means:

• I switch on
• I turn on
• I light

In this sentence, it refers to I turn on the lamp.

Also, encender is a stem-changing verb:

• enciendo
• enciendes
• enciende
• encendemos
• encendéis
• encienden

The e changes to ie in most forms.

Spanish uses definite articles (el, la, los, las) more often than English does.

Here, la lámpara and la mesilla sound natural because they refer to specific, identifiable objects in the situation:

• la lámpara = the lamp
• la mesilla = the bedside table / small table

In context, the speaker is talking about the lamp and table in their room, so Spanish naturally uses the article.

In Spain, mesilla usually means a small table, and very often a bedside table / nightstand.

In this sentence, la mesilla most naturally means the bedside table.

This is a good Spain-specific word to know. In other places, you may also hear:

• mesita de noche
• mesa de noche
• buró (in some countries)

For Spain, mesilla is very natural.

This is a relative clause describing la lámpara.

• la lámpara = the lamp
• que está sobre la mesilla = that is on the bedside table

So que here means that / which.

A literal breakdown:

• la lámpara
• que = that
• está = is
• sobre la mesilla = on the bedside table

So the clause tells you which lamp the speaker means: the one that is on the table.

Because the sentence is talking about location, and location uses estar, not ser.

• está sobre la mesilla = it is on the bedside table

Use estar for where something is:

• El libro está en la mesa.
• La lámpara está sobre la mesilla.

Using es here would be incorrect.

Both can mean on / on top of, and in many cases they are very similar.

• sobre la mesilla
• encima de la mesilla

In this sentence, sobre is perfectly natural and a little more compact.

A useful way to think about it:

• sobre often means on top of / resting on
• encima de also means on top of, and can sometimes feel a bit more explicit

Here, because the lamp is physically sitting on the table, sobre la mesilla works very well.

The verb is leer (to read), and the yo form in the present is leo.

Present tense:

• leo
• lees
• lee
• leemos
• leéis
• leen

So leo is the correct form for I read.

English speakers sometimes expect something like leyo, but that is not how this verb is formed in the present tense.

Un rato means a while or for a little while.

It is an imprecise amount of time, not a fixed length.

So:

• leo un rato = I read for a while

Very common expressions:

• espera un rato = wait a bit
• descanso un rato = I rest for a while
• hablamos un rato = we talk for a while

It sounds natural and everyday.

Spanish often expresses duration without a preposition in cases like this.

So:

• leo un rato = I read for a while
• duermo dos horas = I sleep for two hours
• estudio un poco = I study for a bit

English often needs for, but Spanish often does not.

So leo un rato is the normal structure.

It is natural and correct, because Por la noche is an introductory time phrase.

• Por la noche, enciendo la lámpara...

The comma helps separate the time expression from the main part of the sentence.

In less formal writing, people may sometimes omit it:

• Por la noche enciendo la lámpara...

But with the comma, the sentence is clearer and more polished.

Yes. Spanish often uses the present tense to describe habits and routines.

So this sentence means something like what the speaker usually does at night:

• Por la noche, enciendo la lámpara... y leo un rato.

This is just like English:

• At night, I turn on the lamp and read for a while.

It is the ordinary present tense used for habitual actions.