De elfde student komt.

Because student is a de-word in Dutch: de student.
The ordinal elfde does not change the noun’s article, so you still say de elfde student.

A useful habit is to learn nouns together with their article:

• de student
• het boek
• de tafel

Elfde is an ordinal number: it means a position in a sequence, like first, second, third, eleventh in English.

In this sentence, it is used before a noun, so it behaves like an adjective:

• de elfde student
• de vierde dag
• de twintigste pagina

It comes from the cardinal number elf (eleven) and becomes the ordinal elfde (eleventh).

Dutch ordinals are formed in different ways, but many use -de or -ste:

• vier → vierde
• acht → achtste
• elf → elfde

So elfde is simply the normal ordinal form of elf.

Because elfde is the standard Dutch form. Dutch ordinals are not all built with the same ending.

For elf, the correct form is:

• elfde

So:

• de elfde student = correct
• de elfste student = not standard Dutch

The infinitive is komen (to come).
Here, the subject is singular: de elfde student. That means Dutch uses the third-person singular present tense:

• ik kom
• jij komt
• hij/zij komt
• de student komt
• wij komen

So komt matches the singular subject.

It can often correspond to either one, depending on context.

Dutch frequently uses the simple present where English might use:

• comes
• is coming

So komt may be translated in different ways depending on the situation. Dutch usually does not need a separate progressive form as often as English does.

Because Dutch main clauses usually follow the V2 rule: the finite verb goes in the second position.

In this sentence:

• De elfde student = first element
• komt = second element

If you move another element to the front, the verb still stays second:

• Morgen komt de elfde student.
• Nu komt de elfde student.

That is a very important Dutch word-order rule.

Not in normal standard Dutch. You would normally say:

• De elfde student komt.

Without de, it sounds incomplete or unnatural in ordinary speech.
You might occasionally see article-less language in headlines, notes, or very compressed styles, but not as normal full-sentence Dutch.

Not always. In Dutch, student usually refers to someone in higher education, such as a university or college student.

For a school pupil, Dutch often uses:

• leerling
• sometimes scholier

So this word can be a little narrower than English student.

A rough pronunciation guide is:

• de ≈ duh
• elfde ≈ ELF-duh
• student has stress on the second syllable
• komt has a short vowel and a clearly pronounced final t

The trickiest part for many learners is elfde, because of the consonant cluster in the middle.