Ili elektas portreton kaj memfoton.

Ili means they.

It does not tell you gender. Esperanto ili can refer to:

• a group of men
• a group of women
• a mixed group
• people whose gender is unknown or irrelevant

So it works like English they in that sense.

Elektas is the present-tense form of the verb elekti, meaning to choose or to select.

In Esperanto, verbs have very regular endings:

• -i = infinitive: elekti = to choose
• -as = present: elektas = choose / are choosing
• -is = past: elektis = chose
• -os = future: elektos = will choose

So Ili elektas means They choose or They are choosing.

The -n ending marks the direct object in Esperanto.

In this sentence, the things being chosen are:

• portreton = a portrait
• memfoton = a selfie

Since those are the direct objects of elektas, they take -n.

Compare:

• Ili elektas portreton. = They choose a portrait.
• La portreto estas bela. = The portrait is beautiful.

In the second sentence, portreto is not a direct object, so there is no -n.

Esperanto does have a word for the: la.

But it has no separate word for a/an.

So:

• portreto can mean a portrait or just portrait, depending on context
• la portreto means the portrait

In your sentence:

• Ili elektas portreton kaj memfoton.

this naturally means They choose a portrait and a selfie, unless the context makes them definite.

Portreton breaks down like this:

• portret- = the root, meaning portrait
• -o = noun ending
• -n = direct object ending

So:

• portreto = portrait
• portreton = portrait as a direct object

This is a very common Esperanto pattern.

Yes, memfoton is a compound word.

It is built from:

• mem = self
• foto = photo
• -n = direct object ending

So:

• memfoto = selfie, self-photo
• memfoton = selfie as a direct object

Esperanto often forms words this way by combining meaningful parts.

Kaj means and.

It links the two direct objects:

• portreton
• memfoton

So:

• portreton kaj memfoton = a portrait and a selfie

Both nouns get -n because both are direct objects of elektas.

Yes. Esperanto word order is fairly flexible, mainly because the -n ending helps show what the direct object is.

The normal, straightforward order is:

• Ili elektas portreton kaj memfoton.

But other orders are possible, such as:

• Portreton kaj memfoton ili elektas.

That sounds more marked or emphasized, something like:

• A portrait and a selfie, they choose.

For learners, the standard subject–verb–object order is usually best.

A simple pronunciation guide is:

EE-lee eh-LEK-tahs por-TREH-ton kai mem-FO-ton

A few useful points:

• i sounds like ee
• e sounds like eh
• o sounds like oh
• a sounds like ah
• kaj sounds roughly like kai in English sky without the s
• stress usually falls on the second-to-last syllable

So:

• Ili → stress on I
• elektas → stress on lek
• portreton → stress on tre
• memfoton → stress on fo

It can mean either, depending on context.

Esperanto -as simply marks the present tense. English often has to choose between:

• choose
• are choosing

Esperanto does not always make that distinction explicitly.

So:

• Ili elektas portreton kaj memfoton.
  can mean:
• They choose a portrait and a selfie
• They are choosing a portrait and a selfie

The surrounding context tells you which is more natural.

Because ili is the subject, not the direct object.

In this sentence:

• Ili = the people doing the action
• elektas = the action
• portreton kaj memfoton = the things receiving the action

Only the direct object gets -n here.

So:

• ili = they
• ilin = them

If you said Mi vidas ilin, that would mean I see them, because now them is the direct object.

Yes, memfoto is a normal and understandable Esperanto word for selfie.

It is transparent and easy to understand because it literally means self-photo.

You may sometimes see borrowing or variation in informal use, but memfoto is a clear, standard-style Esperanto formation.