El hombre se dedica a su trabajo.

Because the verb here is dedicarse, not just dedicar.

• dedicar algo a alguien = to dedicate something to someone
  
  • Dedica mucho tiempo a su trabajo. = He dedicates a lot of time to his work.
• dedicarse a algo = to devote oneself to something / to work at something / to be involved in something

So in El hombre se dedica a su trabajo, se is part of the verb structure. It shows that the man is devoting himself to his work.

Dedicarse a is a very common Spanish expression. Its meaning depends a little on context, but common ideas are:

• to devote oneself to
• to be dedicated to
• to work in / be engaged in

In this sentence, it suggests that the man is focused on, committed to, or absorbed in his work.

So it is not just a literal word-for-word equivalent of English dedicate. It behaves like a set phrase: dedicarse a + noun/infinitive.

Examples:

• Se dedica a la música. = He/She devotes himself/herself to music / works in music.
• Se dedica a enseñar. = He/She is dedicated to teaching / works as a teacher.

Because dedicarse normally takes a.

This is just how the verb pattern works:

• dedicarse a + noun
• dedicarse a + infinitive

So:

• se dedica a su trabajo
• se dedica a estudiar
• se dedica a la medicina

This a does not mean movement here. It is simply the preposition required by the verb.

Because the subject is El hombre, which is he.

Present tense of dedicarse:

• yo me dedico
• tú te dedicas
• él / ella / usted se dedica
• nosotros/as nos dedicamos
• vosotros/as os dedicáis
• ellos / ellas / ustedes se dedican

Since el hombre = he, the correct form is se dedica.

Su trabajo means his work or his job, so it clearly links the work to the man.

Compare:

• su trabajo = his work / his job
• el trabajo = work in general / the work

In this sentence, su trabajo makes it personal: the man is dedicated to his own work.

Also remember that su can mean:

• his
• her
• its
• your (formal)
• their

Here, because the subject is el hombre, learners naturally understand it as his.

It can suggest either, depending on context.

Trabajo is a broad word and can mean:

• work in a general sense
• job
• profession
• occupation
• task/workload in some contexts

In se dedica a su trabajo, it usually sounds like his work or his job/profession rather than one specific task.

Because Spanish usually uses an article with a noun when referring to a specific person or thing.

• El hombre = the man

If you said Un hombre, it would mean a man, not the man.

So El hombre tells us we are talking about a specific man, not just any man.

Not exactly.

• Trabaja simply means he works.
• Se dedica a su trabajo suggests more than that: commitment, devotion, focus, or serious involvement.

So se dedica a su trabajo often sounds stronger than trabaja.

Compare:

• El hombre trabaja. = The man works.
• El hombre se dedica a su trabajo. = The man is dedicated to his work / devotes himself to his work.

No, not in this meaning.

Dedicar without se usually needs a direct object:

• El hombre dedica mucho tiempo a su trabajo.
• El hombre dedica su vida a su trabajo.

But if you want the idea he devotes himself to his work, you need dedicarse:

• El hombre se dedica a su trabajo.

So removing se changes the grammar and makes the sentence incomplete unless you add something that is being dedicated.

Yes, but El hombre se dedica a su trabajo is the most neutral and natural order.

Spanish word order is fairly flexible, so you might also see:

• Se dedica a su trabajo el hombre.

But that version sounds marked, literary, or context-dependent. It might be used for emphasis, contrast, or style.

For everyday neutral Spanish, keep:

• El hombre se dedica a su trabajo.

It is usually taught as a pronominal verb, and many learners group that together with reflexive verbs.

Why? Because it uses reflexive-looking pronouns:

• me, te, se, nos, os, se

But the meaning is not always literally reflexive in the English sense. In dedicarse a, the pronoun is part of the verbal structure, and the whole expression has its own meaning.

So for learning purposes, it is helpful to treat dedicarse a as a fixed pattern:

• me dedico a...
• te dedicas a...
• se dedica a...

Yes. It can be followed by:

• a + noun
• a + infinitive

Examples:

• Se dedica a su trabajo.
• Se dedica a la pintura.
• Se dedica a estudiar.
• Se dedica a ayudar a los demás.

So once you learn the pattern dedicarse a, you can use it in many situations.