Μου αρέσει να βάφω μικρά έπιπλα, αλλά σήμερα θέλω να βάψω μόνο το ράφι στο σαλόνι.

Because Greek expresses this idea differently from English.

Μου αρέσει literally means something like It is pleasing to me:

• μου = to me
• αρέσει = is pleasing / pleases

So instead of saying I like X, Greek often says X pleases me.

That is why the sentence starts with Μου αρέσει... and not with a form meaning I like in the English sense.

Because the thing that pleases the speaker is the whole activity να βάφω μικρά έπιπλα.

A whole activity or clause is treated as singular, so Greek uses αρέσει.

Compare:

• Μου αρέσει να βάφω μικρά έπιπλα. = I like painting small furniture items.
  
  • The subject is the whole action.
• Μου αρέσουν τα μικρά έπιπλα. = I like the small pieces of furniture.
  
  • Now the subject is τα μικρά έπιπλα, which is plural, so Greek uses αρέσουν.

να introduces a dependent verb form, often where English would use an infinitive such as to paint.

So:

• να βάφω = to paint / painting
• να βάψω = to paint

Modern Greek does not normally use an infinitive the way English does. After verbs like αρέσει and θέλω, Greek uses να + verb.

So:

• Μου αρέσει να βάφω... = I like to paint / I like painting...
• θέλω να βάψω... = I want to paint...

This is one of the most important points in the sentence: aspect.

• βάφω = imperfective
• βάψω = perfective

Very roughly:

• imperfective focuses on an activity as ongoing, repeated, habitual, or general
• perfective focuses on a single complete action

So here:

• Μου αρέσει να βάφω μικρά έπιπλα
  = I like painting small furniture items in general
  = a repeated or general activity

• σήμερα θέλω να βάψω μόνο το ράφι
  = today I want to paint only the shelf
  = one specific completed task

That contrast is very natural in Greek.

You could, but it would change the meaning.

• θέλω να βάψω = I want to paint it / get it painted
  
  • one specific action
• θέλω να βάφω = I want to be painting / I want to paint as an ongoing or repeated activity

In this sentence, today and only the shelf make it clear that we are talking about one specific job, so βάψω is the natural choice.

Because the wanting is happening now.

The sentence means that today, right now, I want to paint only the shelf. Greek uses present θέλω because the desire is present.

This is similar to English:

• Today I want to paint only the shelf.

You do not need θα after θέλω here.

Compare:

• Θέλω να βάψω το ράφι. = I want to paint the shelf.
• Θα βάψω το ράφι. = I will paint the shelf.

The first expresses desire; the second expresses future action.

Because Greek often leaves subject pronouns out when they are not needed.

The verb ending already tells you the subject:

• θέλω = I want
• βάφω = I paint
• βάψω = I paint in this να-clause

So εγώ is unnecessary unless you want emphasis or contrast.

For example:

• Εγώ θέλω να βάψω μόνο το ράφι, όχι εσύ.
  = I want to paint only the shelf, not you.

Without that kind of emphasis, Greek normally omits the pronoun.

Because έπιπλα is neuter plural, and the adjective has to agree with it.

• μικρός, μικρή, μικρό = small
• neuter plural = μικρά

So:

• μικρά έπιπλα = small pieces of furniture / small furniture items

The agreement is:

• μικρά = neuter plural
• έπιπλα = neuter plural

Because the sentence is speaking generally, not about a specific set of furniture.

• να βάφω μικρά έπιπλα = to paint small furniture items in general

If you added an article, the meaning would become more specific:

• να βάφω τα μικρά έπιπλα = to paint the small pieces of furniture

So the lack of article here matches the broad, general meaning.

Almost, but not quite.

The singular is:

• το έπιπλο = a piece of furniture / a furniture item

The plural is:

• τα έπιπλα = furniture items / pieces of furniture / furniture

English furniture is usually uncountable, but Greek often uses a countable noun for individual items. So μικρά έπιπλα is best understood as small furniture items or small pieces of furniture.

Because ράφι is a neuter singular noun, and here it is a specific direct object: the shelf.

• το = the for neuter singular nouns
• ράφι = shelf

So:

• το ράφι = the shelf

It is specific because the speaker means one particular shelf, not shelves in general.

Because many neuter nouns in Greek have the same form in the nominative and the accusative.

So:

• nominative: το ράφι
• accusative: το ράφι

In this sentence, το ράφι is the direct object of βάψω, so it is accusative, but it looks the same as the nominative form.

That is very common with neuter nouns in Greek.

στο is the contracted form of σε + το.

• σε = in / at / to / on
• το = the
• σε το → στο

So:

• στο σαλόνι = in the living room

These contractions are standard in Greek:

• στο
• στη(ν)
• στον
• στα

Here μόνο modifies το ράφι.

So:

• θέλω να βάψω μόνο το ράφι = I want to paint only the shelf

That means the speaker wants to paint the shelf and nothing else.

Its position matters. For example:

• θέλω μόνο να βάψω το ράφι can sound more like all I want is to paint the shelf
• θέλω να βάψω μόνο το ράφι clearly means only the shelf

So the placement of μόνο helps show exactly what is being limited.

Usually no, not in this kind of sentence.

βάφω usually means to apply paint or color to something, or more generally to dye / color something.

So it is the right verb for things like:

• walls
• doors
• shelves
• furniture
• hair
• eggs

If you mean to paint/draw a picture, Greek more often uses ζωγραφίζω.

So in this sentence, βάφω / βάψω means paint in the sense of put paint on furniture.