El frío puede matar la planta.

Because frío is being used here as a noun meaning the cold / cold weather / low temperatures, so Spanish normally uses the definite article: el frío.

Compare:

• Hace frío. = It’s cold.
  Here frío is not the subject; it is part of the expression hacer frío.
• El frío puede matar la planta. = The cold can kill the plant.
  Here el frío is the subject of the sentence.

So the article is needed because frío is acting like a thing.

Puede is the 3rd person singular present of poder (to be able to / can).

The subject is el frío, which is singular, so the verb must also be singular:

• el frío puede
• not el frío pueden

This is the same idea as in English:

• The cold can kill...
• not The cold can kills...

After poder, Spanish uses an infinitive:

• puede matar
• pueden comer
• podemos salir

So puede matar means can kill.

This is a very common pattern:

• Puedo hablar español. = I can speak Spanish.
• La lluvia puede dañar la casa. = The rain can damage the house.

La planta usually suggests a specific plant that the speaker and listener already know about, for example a plant in the house or garden.

• la planta = the plant
• una planta = a plant

So:

• El frío puede matar la planta. = The cold can kill the plant.
• El frío puede matar una planta. = The cold can kill a plant.

In some contexts, Spanish can also use the definite article for a more general idea, but in a simple sentence like this, learners will usually understand la planta as a particular plant.

Yes, but the meaning changes slightly.

• El frío puede matar la planta. = The cold can kill the plant.
  This expresses possibility or ability.
• El frío mata la planta. = The cold kills the plant.
  This sounds more like a general fact, a stronger statement.

So puede makes the sentence less absolute.

Yes, but the normal, neutral order is:

• El frío puede matar la planta.

Spanish word order is more flexible than English. For emphasis, you might hear things like:

• La planta la puede matar el frío.

That version emphasizes la planta, but it is more marked and less basic for a learner.

If you are learning standard sentence structure, El frío puede matar la planta is the best model to follow.

Here frío means cold, especially cold weather, cold temperatures, or the cold as a force that affects things.

It does not mean someone emotionally being cold in this sentence. The context with matar la planta makes it clearly physical temperature.

So el frío can refer to:

• cold weather
• frost-like conditions in a general sense
• low temperatures

The written accent in frío shows that the í is stressed and pronounced separately from the o.

So it is pronounced as frí-o, with two syllables.

Without the accent, Spanish pronunciation rules would suggest a different pattern. The accent helps show the correct pronunciation and the break between the vowels.

No, planta can mean more than one thing in Spanish. Common meanings include:

• plant = a living plant
• floor / storey of a building

In this sentence, because of el frío puede matar..., it clearly means plant.

Context usually makes the meaning obvious.

Because la planta is the direct object of matar.

In Spanish, direct objects usually do not need a preposition:

• matar la planta
• comprar el libro
• ver la casa

The main exception learners notice is the personal a, used before specific people:

• Veo a María.

But la planta is not a person, so there is no a here.

Yes. It is a completely natural and correct sentence in Spain.

It sounds like a normal warning or observation, for example about gardening:

• Mete la maceta dentro; el frío puede matar la planta.

So it is good, standard Spanish and would be understood everywhere in the Spanish-speaking world.