El campeón practica todos los días en el estadio.

In Spanish, singular countable nouns almost always need an article (definite or indefinite) unless something else (like a possessive) is in front of them.

• El campeón = the champion (a specific one we have in mind).
• Un campeón = a champion (not a specific one).
• Mi campeón = my champion (no article needed because mi is there).

So in this sentence, Spanish naturally says El campeón practica…; leaving out el would sound incomplete in normal speech. There are places you can drop the article (e.g., headlines, labels, or some fixed expressions), but in a regular sentence like this, el is required.

Campeón is the masculine form and campeona is the feminine form:

• el campeón = the (male) champion
• la campeona = the (female) champion

If you’re talking about a woman, you should say:

• La campeona practica todos los días en el estadio.

The noun changes ending -ón → -ona, and the article changes el → la.

Spanish has regular stress rules:

• Words ending in a vowel, n, or s are usually stressed on the second-to-last syllable.
• Words ending in any other consonant are usually stressed on the last syllable.

Campeón ends in n, so normally it would be stressed on -pe-: CAM-pe-on.
But the written accent (´) on -ón tells you the stress moves to the last syllable:

• ca-mpe-ÓN

So the correct pronunciation is cam-pe-ÓN.

Note: in the plural, campeones has no accent mark because now the natural stress falls on -o- (cam-pe-O-nes), which already matches the normal rule.

Practica is the third person singular (he/she/it) form of practicar in the simple present:

Conjugation of practicar in the present tense (indicative):

• yo practico – I practice
• tú practicas – you practice (informal)
• él / ella / usted practica – he / she / you (formal) practice
• nosotros practicamos – we practice
• ustedes practican – you all practice
• ellos / ellas practican – they practice

In the sentence, the subject is El campeón (he), so we must use practica:

• El campeón practica… = The champion practices…

Yes. Práctica (with an accent) can be a noun meaning practice, training, rehearsal, etc.:

• La práctica es importante. – Practice is important.
• Tengo práctica de fútbol. – I have soccer practice.

In your sentence, practica has no accent and appears after a clear subject (El campeón), so it’s the verb form (he/she practices). Position and the accent mark help you distinguish verb practica from noun práctica.

Spanish uses the simple present much more than English to talk about:

• habits and routines
• general truths
• scheduled actions

So:

• El campeón practica todos los días…
  = “The champion practices every day…”

If you said está practicando, you’d be focusing on right now:

• El campeón está practicando en el estadio.
  = The champion is (currently) practicing at the stadium.

For habits like “every day,” the simple present practica is the natural choice.

Yes, you can say entrena, and it’s very common in sports contexts:

• El campeón entrena todos los días en el estadio.

Subtle difference:

• practicar – to practice something specific: skills, moves, plays, an instrument, etc.
• entrenar – to train (often more about physical training, coaching, workout routines).

In everyday speech about athletes, entrenar is extremely common, but practicar is also perfectly correct and natural.

Because días is plural, so both the determiner and the adjective must also be plural:

• todo (singular) → todos (plural)
• el (singular) → los (plural)
• día (singular) → días (plural)

So the correct phrase is:

• todos los días = every day, all the days

Compare:

• todo el día – all day (singular, one whole day)
• todos los días – every day (plural, all the days)

Both are usually translated as “every day”, and in most contexts they’re interchangeable:

• El campeón practica todos los días.
• El campeón practica cada día.

Todos los días is more common in everyday speech.
Cada día can sound slightly more emphatic or stylistic, especially in writing, but the difference is small.

The singular is día and the plural is días, both with an accent.

Reason: Without the written accent, dia would normally be pronounced [DYA] (a diphthong), with the stress on the a. But we actually say DÍ-a, two syllables, with the stress on í. The accent mark:

• breaks the diphthong (di-a, two syllables)
• shows that the stress is on í

So:

• día = DÍ-a
• días = DÍ-as

En and a express different ideas:

• en el estadio = in/at the stadium (location)
• al estadio = to the stadium (direction, destination)
  (al = a + el)

Your sentence describes where the champion practices, not where he is going:

• El campeón practica todos los días en el estadio.
  = The champion practices every day at the stadium.

If you wanted to say “He goes to the stadium every day,” you’d use al:

• El campeón va todos los días al estadio.

Estadio is a masculine noun in Spanish, so it takes masculine articles and adjectives:

• el estadio – the stadium
• un estadio – a stadium
• este estadio – this stadium

There is no feminine form la estadio. The gender of many nouns (like estadio) is arbitrary and must be memorized.

Yes, you can move the time phrase todos los días:

• El campeón practica todos los días en el estadio.
• El campeón practica en el estadio todos los días.

Both are correct and natural. Spanish allows fairly flexible placement of time and place expressions. The meaning is the same; the change is just a slight shift in emphasis (whether you’re highlighting “every day” a bit earlier or the place first), but in normal conversation they’re functionally equivalent.

Yes, if the subject is clear from context, Spanish can omit it because it’s a pro-drop language.

• Practica todos los días en el estadio.
  = “(He/She) practices every day at the stadium.”

In conversation, you’d usually have mentioned the person (the champion) earlier, then continue with sentences like this without repeating the subject each time.