Η μαθήτρια μπερδεύει ακόμα τον ενικό με τον πληθυντικό.

Η is the feminine singular definite article, meaning the.

Here it goes with μαθήτρια:

• η μαθήτρια = the student (female)

Greek articles change for gender, number, and case, so you will see different forms such as ο, η, το in the nominative singular.

Μαθήτρια means female student / schoolgirl. It is the feminine form.

Compare:

• ο μαθητής = the male student
• η μαθήτρια = the female student

So the sentence is specifically talking about a female student.

Μπερδεύει is:

• present tense
• third person singular
• from the verb μπερδεύω = to confuse / to mix up

So:

• μπερδεύω = I confuse / I mix up
• μπερδεύει = she/he/it confuses / mixes up

With η μαθήτρια, it means the student confuses / is still confusing.

Because this sentence uses the active form of the verb:

• μπερδεύω κάτι με κάτι = I confuse one thing with another

So:

• Η μαθήτρια μπερδεύει τον ενικό με τον πληθυντικό = The student confuses the singular with the plural.

By contrast:

• μπερδεύεται usually means gets confused / is confused

So:

• Η μαθήτρια μπερδεύεται = The student gets confused / is confused.

Here ακόμα means still.

So the idea is:

• Η μαθήτρια μπερδεύει ακόμα... = The student is still confusing...

In other contexts, ακόμα can also mean even or yet, but still is the natural meaning in this sentence.

Yes. Greek word order is fairly flexible, and adverbs like ακόμα can move around.

For example, all of these are possible:

• Η μαθήτρια μπερδεύει ακόμα τον ενικό με τον πληθυντικό.
• Η μαθήτρια ακόμα μπερδεύει τον ενικό με τον πληθυντικό.
• Ακόμα η μαθήτρια μπερδεύει τον ενικό με τον πληθυντικό.

The version in your sentence is very natural. Moving ακόμα can slightly change emphasis, but not the basic meaning.

Ενικός and πληθυντικός are grammatical terms meaning:

• ενικός = singular
• πληθυντικός = plural

They are masculine here because they originally refer to an understood masculine noun, usually αριθμός (number), as in:

• τον ενικό αριθμό = the singular number
• τον πληθυντικό αριθμό = the plural number

In practice, Greek often leaves αριθμό out, so you just say:

• τον ενικό
• τον πληθυντικό

Because these words are objects in the sentence, so they are in the accusative case.

The pattern is:

• μπερδεύω κάτι με κάτι = confuse one thing with another

So both grammatical terms appear as objects:

• τον ενικό
• τον πληθυντικό

Masculine singular article:

• nominative: ο
• accusative: τον

That is why you see τον, not ο.

The verb μπερδεύω commonly uses the pattern:

• μπερδεύω X με Y = I confuse X with Y

So:

• μπερδεύει τον ενικό με τον πληθυντικό = she confuses the singular with the plural

This is very close to English:

• confuse A with B

Originally they are adjectives, but here they are being used substantively, which means as nouns.

So although:

• ενικός literally means singular
• πληθυντικός literally means plural

in grammar talk they function like nouns:

• the singular
• the plural

English does this too.

Greek uses the definite article more often than English, especially with:

• abstract concepts
• school subjects
• grammatical categories
• general classes of things

So Greek naturally says:

• τον ενικό
• τον πληθυντικό

where English may simply say:

• singular
• plural

or

• the singular
• the plural, depending on the sentence.

A rough pronunciation is:

• beh-rdheh-VEE

A few useful points:

• μπ at the beginning of a word is usually pronounced like b
• ευ here sounds like ev because the next sound is voiced
• ει sounds like ee
• the stress is on -δεύ-

So:

• μπερδεύει ≈ berdévi

Yes. Ακόμα and ακόμη are both used, and in most contexts they mean the same thing.

Here both would work:

• Η μαθήτρια μπερδεύει ακόμα τον ενικό με τον πληθυντικό.
• Η μαθήτρια μπερδεύει ακόμη τον ενικό με τον πληθυντικό.

In everyday modern Greek, ακόμα is extremely common.

Usually it means the concepts in general: she still mixes up singular and plural.

Because Greek uses the article with these grammar terms, τον ενικό and τον πληθυντικό are best understood as:

• the singular
• the plural

meaning the grammatical categories, not necessarily one single word form each.