La fono aspektas malnova.

• la = the definite article, the
• fono = a noun, background
• aspektas = a verb in the present tense, looks / appears
• malnova = an adjective, old

So the structure is:

la + noun + verb + adjective

This is very similar to English The background looks old.

In Esperanto, all present-tense verbs end in -as.

So:

• aspekti = to look, to appear
• aspektas = looks / is looking / appears

A few useful comparisons:

• aspektis = looked / appeared
• aspektos = will look / will appear
• aspektu = look! / may it look

The verb ending tells you the tense, and it does not change for different subjects. So:

• mi aspektas
• vi aspektas
• ĝi aspektas

all use -as in the present.

The prefix mal- creates the opposite of a word.

• nova = new
• malnova = old

This is a very common Esperanto pattern. For example:

• bona = good → malbona = bad
• granda = big → malgranda = small
• juna = young → maljuna = old

So malnova literally means not new, and in normal usage that means old.

Because malnova describes the noun fono.

In Esperanto:

• adjectives end in -a
• adverbs end in -e

Here, malnova is a predicate adjective after the verb aspektas. It tells you what the background seems to be like.

Compare:

• La fono aspektas malnova. = The background looks old.
  (malnova describes fono)
• La fono aspektas malnove. = The background looks in an old way / has an old-looking appearance.
  This is possible in some contexts, but it is less direct and less natural for this basic meaning.

So for looks old, the adjective malnova is the normal choice.

There is no -n because malnova is not a direct object here.

In La fono aspektas malnova:

• la fono is the subject
• aspektas is the verb
• malnova is a predicate adjective describing the subject

Predicate adjectives normally match the subject, so here it stays in the basic singular form:

• malnova

You would not use malnovan here.

Compare:

• Mi vidas malnovan fonon. = I see an old background.
  Here fonon is a direct object, so it takes -n, and the adjective agrees: malnovan.
• La fono aspektas malnova. = The background looks old.
  No direct object, so no -n.

La is the Esperanto definite article, meaning the.

So:

• fono = background / a background
• la fono = the background

Esperanto has only one article, la, and it does not change for gender, number, or case.

There is no separate word for English a/an. So:

• fono can mean a background or just background, depending on context
• la fono specifically means the background

Not necessarily. Aspektas means looks or appears, so it describes appearance, not certainty.

• La fono estas malnova. = The background is old.
  This states it as a fact.
• La fono aspektas malnova. = The background looks old.
  This only describes how it seems.

So this sentence leaves open the possibility that the background only appears old.

Yes. In many contexts, aspekti can mean:

• to look
• to appear
• to seem in appearance

So La fono aspektas malnova could be understood as:

• The background looks old
• The background appears old

Usually looks old is the most natural English translation here.

Because fono is singular.

In Esperanto, adjectives agree with the nouns they describe in number and case.

Here:

• fono = singular
• so the adjective is also singular: malnova

If the noun were plural, the adjective would also be plural:

• La fonoj aspektas malnovaj. = The backgrounds look old.

Esperanto word order is fairly flexible, but the normal order here is:

La fono aspektas malnova.

That is the clearest and most neutral order.

You might sometimes see a different order for emphasis, but for learners, it is best to stick with: subject + verb + complement

So this sentence is a good standard model.

Yes, fono is a normal Esperanto word. It usually means background.

Depending on context, it can refer to:

• the background of an image
• the background in a design or interface
• a backdrop
• sometimes background in a more general visual sense

So in this sentence, La fono aspektas malnova, the idea is that the background has an old-looking appearance.

Yes, you could.

• aspektas malnova = looks old, appears old in appearance
• ŝajnas malnova = seems old

The difference is subtle:

• aspekti focuses more on outward appearance
• ŝajni focuses more on seeming in general

For a visual judgment about how something looks, aspektas malnova is especially natural.