No puedo cargar la caja.

In Spanish, the basic negative pattern is no + verb.

So:

• Puedo = I can
• No puedo = I can’t / I cannot

Spanish does not usually use a separate word like do for negation, so you simply put no before the conjugated verb.

Puedo is the 1st person singular (I) form of the verb poder, which means to be able to / can.

Present tense of poder:

• yo puedo = I can
• tú puedes = you can
• él/ella/usted puede = he/she/you can
• nosotros/nosotras podemos = we can
• vosotros/vosotras podéis = you all can
• ellos/ellas/ustedes pueden = they/you all can

So puedo tells you the subject is I, even though yo is not written.

Spanish often omits subject pronouns because the verb ending already shows who the subject is.

• (Yo) puedo = I can

Including yo is possible, but usually unnecessary unless you want emphasis or contrast:

• Yo no puedo cargar la caja, pero él sí.
  I can’t carry the box, but he can.

So No puedo cargar la caja is the normal, natural way to say it.

After a conjugated verb like poder, the next verb usually stays in the infinitive.

So the structure is:

• puedo cargar = I can carry
• literally: I am able to carry

This is very common in Spanish:

• Quiero comer = I want to eat
• Debo estudiar = I must study
• Puedo cargar = I can carry

Only the first verb is conjugated here; the second one stays in the infinitive.

In this sentence, cargar most naturally means to carry, to lift, or to haul, depending on context.

But cargar is a flexible verb and can also mean things like:

• to load
• to charge (for example, a battery)
• to upload in some contexts
• to burden

With la caja (the box), the likely meaning is carry or lift:

• No puedo cargar la caja. = I can’t carry/lift the box.

Spanish often uses the definite article more regularly than English. Here, la caja means the box.

• caja = box
• la caja = the box

Without an article, caja would usually sound incomplete in this sentence unless there were some special context.

Also, caja is a feminine noun, so it takes la, not el.

The noun caja is grammatically feminine, so it uses feminine articles and adjectives:

• la caja
• una caja
• la caja pesada = the heavy box

A common pattern is that nouns ending in -a are often feminine, though not always. Caja follows that common pattern.

Remember that grammatical gender in Spanish is about noun class, not biological sex. A box is not female in any real-world sense; it just belongs to the feminine grammatical category.

This follows a very normal Spanish word order:

no + conjugated verb + infinitive + object

So:

• No = not
• puedo = I can
• cargar = carry
• la caja = the box

This is directly comparable to English:

• I can’t carry the box

Spanish word order can sometimes change for emphasis, but this version is the standard, neutral order.

Yes, in some contexts cargar la caja could be understood as to load the box or to load up the box, but that is less likely as a first interpretation.

Usually:

• cargar una caja often suggests carrying/lifting a box
• cargar la caja en el coche = to load the box into the car

So context decides the best translation. If the meaning has already been given to the learner, then that context should guide which English meaning fits best.

Sometimes yes, but llevar and cargar are not exactly the same.

• cargar often emphasizes the physical effort of lifting or bearing weight
• llevar more generally means to take / to carry / to bring

So:

• No puedo cargar la caja = I can’t lift/carry the box (it may be too heavy)
• No puedo llevar la caja = I can’t take/carry the box

If the problem is weight or physical strain, cargar is often the better choice.

You would use the direct object pronoun la, because caja is feminine singular.

• No puedo cargar la caja.
• No la puedo cargar.
• No puedo cargarla.

Both pronoun positions are correct:

1. before the conjugated verb: No la puedo cargar
2. attached to the infinitive: No puedo cargarla

Both mean I can’t carry it.

In standard Peninsular Spanish pronunciation:

• caja sounds roughly like KA-ha

More precisely:

• ca = ka
• j = a strong throaty sound, like the ch in Scottish loch or German Bach
• the stress is on the first syllable: CA-ja

So: CA-ha

The j is not pronounced like the English j in job.

Usually, yes, but not always. Poder can refer to different kinds of ability:

• physical ability: I’m not strong enough
• practical possibility: I’m not able to do it right now
• permission in other contexts: can / may

In this sentence, with the box, the most natural reading is physical or practical inability:

• it’s too heavy
• your hands are full
• you’re injured
• you’re unable for some reason

So the exact nuance depends on context.

You would change the form of poder:

• No puedes cargar la caja. = You can’t carry the box. informal singular
• No puede cargar la caja. = You can’t carry the box. formal singular
• No podéis cargar la caja. = You all can’t carry the box. informal plural in Spain
• No pueden cargar la caja. = You all can’t carry the box. formal plural / common in Latin America

The rest of the sentence stays the same.