O medidor de energia fica perto do quadro de luz.

O is the masculine singular definite article, meaning the.

It is used because medidor is a masculine singular noun:

• o medidor = the meter

In Portuguese, nouns usually need an article more often than in English, especially in normal descriptive sentences like this one.

Yes. Medidor comes from the verb medir, which means to measure.

So:

• medir = to measure
• medidor = meter / measuring device

This is a very common pattern in Portuguese:

• computar → computador
• aspirar → aspirador
• medir → medidor

Here, medidor de energia means electric meter / energy meter.

Portuguese often uses noun + de + noun where English might use a noun acting like an adjective.

So:

• medidor de energia = literally meter of energy
• natural English = energy meter / electric meter

This structure is extremely common in Portuguese:

• conta de luz = electricity bill
• caixa de ferramentas = toolbox
• sala de aula = classroom

So de energia is the normal, natural way to express what kind of meter it is.

In Brazilian Portuguese, ficar is often used to talk about location, especially when saying where something is situated.

So:

• fica perto = is located near / is near

This is very natural in everyday Portuguese.

Compare:

• O medidor de energia fica perto do quadro de luz.
• O medidor de energia está perto do quadro de luz.

Both can work, but fica often sounds more like is located, while está simply states where it is at the moment. In many practical contexts, fica is the more idiomatic choice.

Perto means near or close, but in Portuguese it normally appears with de:

• perto de = near / close to

So:

• perto do quadro de luz = near the electrical panel

This is just how the expression works in Portuguese. You can think of it as a fixed pattern:

• longe de = far from
• perto de = near / close to

Because de + o contracts to do.

So:

• perto de o quadro → perto do quadro

This kind of contraction is very common in Portuguese:

• de + o = do
• de + a = da
• de + os = dos
• de + as = das

Examples:

• perto do carro = near the car
• longe da escola = far from the school

In Brazilian Portuguese, quadro de luz usually refers to the electrical panel, breaker panel, or fuse box in a house or building.

Literally, it looks like:

• quadro = panel / board
• de luz = of light

But in real usage, it refers to the place where the electrical circuits and breakers are organized.

Depending on region and context, you may also hear:

• quadro elétrico
• quadro de energia
• caixa de disjuntores

But quadro de luz is very common and natural in Brazil.

That is just a very common everyday Brazilian Portuguese usage.

In Brazil, luz often refers not only to light, but also more broadly to electricity, especially in household contexts.

For example:

• conta de luz = electricity bill
• quadro de luz = electrical panel
• cortar a luz = cut off the electricity

So even though luz literally means light, it often stands for electrical power in daily speech.

Because in expressions like medidor de energia and quadro de luz, the second noun often appears without an article.

These are basically set noun phrases:

• medidor de energia
• quadro de luz

If you added an article, it would often sound more specific:

• medidor da energia = meter of the energy
• quadro da luz = panel of the light/electricity

That usually does not sound like the normal generic label for these objects. For naming things, Portuguese often prefers the bare form:

• sapato de couro = leather shoe
• copo de vidro = glass cup
• medidor de energia = energy meter

Yes, you can.

• fica perto do quadro de luz = is located near the electrical panel
• está perto do quadro de luz = is near the electrical panel

Both are understandable and natural. The version with fica often sounds a little more like a permanent or usual location, while está can sound more neutral or more immediate.

In many real situations, either one would be fine.

The given order is the most natural neutral order:

• O medidor de energia fica perto do quadro de luz.

Portuguese usually follows subject + verb + complement, just like English.

You can change the order for emphasis, but it may sound less neutral:

• Perto do quadro de luz fica o medidor de energia.

That is grammatically possible, but it sounds more marked or formal. For everyday speech, the original sentence is best.

A simple approximate pronunciation guide:

• medidor ≈ meh-jee-DOR
• energia ≈ eh-nehr-ZHEE-ah
• quadro ≈ KWA-droh

A few details for Brazilian Portuguese:

• In many accents, the d in medidor can sound a bit like j in English before i.
• The g in energia sounds like the s in measure.
• qu in quadro sounds like kw.

A rough full-sentence approximation:

• O medidor de energia fica perto do quadro de luz
• ≈ oo meh-jee-DOR djee eh-nehr-ZHEE-ah FEE-kah PEHR-too doo KWA-droh djee looz

This is only an approximation, but it can help at first.

Yes, energia is feminine:

• a energia

But that does not change medidor, because medidor is the main noun of the phrase.

In:

• o medidor de energia

the article o agrees with medidor, not with energia.

This is an important pattern in Portuguese:

• a conta de luz → conta is feminine, so a
• o medidor de energia → medidor is masculine, so o

The noun after de does not control the article of the whole phrase.

Yes, in some regions or in informal speech, people may say relógio de luz to mean the electricity meter.

Literally, relógio means clock or watch, but colloquially it can be used for meter-like devices.

So you may hear:

• medidor de energia
• medidor de luz
• relógio de luz

Among these, medidor de energia is a clear, standard, widely understandable term.