Ο υπάλληλος είπε ότι δεν μπορείς να υποβάλεις ξανά την αίτηση σήμερα.

Ο υπάλληλος is the subject of the main verb είπε.

• ο = the for a masculine singular noun in the nominative
• υπάλληλος = employee / clerk / staff member

So Ο υπάλληλος is nominative singular masculine: the employee / the clerk.

A useful detail: υπάλληλος ends in -ος, which often looks masculine, but the word can refer to a man or a woman depending on context. Here, the article ο shows that it is masculine in this sentence.

Είπε is the aorist form of λέω (to say / tell).

Here it means said:

• λέει = he/she says
• είπε = he/she said

So Ο υπάλληλος είπε... means The employee said...

This is the normal simple past form for a completed action.

Ότι introduces a content clause, like English that:

• είπε ότι... = said that...

So:

• Ο υπάλληλος είπε ότι... = The employee said that...

In everyday Greek, πως can often be used in the same way:

• είπε ότι...
• είπε πως...

Both are common in this kind of sentence.

Because the subject changes inside the ότι clause.

Main clause:

• Ο υπάλληλος είπε = The employee said

Subordinate clause:

• δεν μπορείς να... = you cannot...

So the employee is the one doing the speaking, but the person who cannot submit is you.

Greek often leaves subject pronouns unstated when the verb ending already shows the person.
Here μπορείς means:

• you can
• with δεν: you cannot

The hidden subject is εσύ (you), but Greek does not need to say it.

Δεν is the normal negation used with finite verbs in Greek. It means not.

So:

• μπορείς = you can
• δεν μπορείς = you cannot / you can’t

It goes directly before the verb:

• δεν μπορείς
• δεν είπε
• δεν θέλω

Να introduces a subordinate verb form, often called the subjunctive in traditional grammar.

After verbs like μπορώ (can / be able to), Greek normally uses:

• μπορώ να + verb
• μπορείς να + verb
• μπορεί να + verb

So:

• μπορείς να υποβάλεις = you can submit

Greek does not usually use an infinitive the way English does.
English says you can submit.
Greek says, more literally, you can that-you-submit, using να.

This is a very common learner question.

The dictionary form is υποβάλλω = I submit.
But after να, Greek often uses either an imperfective or perfective form, depending on the meaning.

Here:

• να υποβάλεις = perfective, one complete action: to submit
• να υποβάλλεις = imperfective, more like ongoing/repeated submitting

Because the sentence is about a single complete act of submitting the application again, να υποβάλεις is the natural choice.

So:

• δεν μπορείς να υποβάλεις ξανά την αίτηση σήμερα = you cannot submit the application again today

This is one of those places where Greek expresses aspect very clearly.

Ξανά means again.

In this sentence:

• να υποβάλεις ξανά την αίτηση = to submit the application again

Its position is normal and natural. Greek word order is somewhat flexible, but ξανά often appears near the verb it modifies.

You may also hear similar placements in other sentences, but here it clearly modifies υποβάλεις.

Την αίτηση is the direct object of υποβάλεις.

• η αίτηση = the application (nominative)
• την αίτηση = the application (accusative)

Because it is the thing being submitted, Greek uses the accusative:

• υποβάλλω την αίτηση = I submit the application

So in the sentence:

• να υποβάλεις ξανά την αίτηση = to submit the application again

Yes, σήμερα (today) can move around more than its English equivalent, depending on emphasis.

The given sentence:

• Ο υπάλληλος είπε ότι δεν μπορείς να υποβάλεις ξανά την αίτηση σήμερα.

This is perfectly natural and neutral.

You could also hear:

• Ο υπάλληλος είπε ότι σήμερα δεν μπορείς να υποβάλεις ξανά την αίτηση.
• Ο υπάλληλος είπε ότι δεν μπορείς σήμερα να υποβάλεις ξανά την αίτηση.

These all mean roughly the same thing, but the emphasis shifts slightly.
Putting σήμερα at the end is very common and sounds natural.

It can vary by context.

Υπάλληλος is a general word meaning something like:

• employee
• staff member
• clerk
• sometimes official, especially in an office or service context

So if this sentence is about an office, a public service desk, or administration, English might naturally translate it as the clerk or the employee.

The exact best translation depends on the situation, but the Greek word itself is broad.

Yes, and this is a very useful distinction.

• ότι = that
• ό,τι = whatever / anything that

In your sentence, it is definitely ότι:

• είπε ότι... = said that...

If it were ό,τι, the meaning would be completely different.

So the comma matters in writing:

• ότι = conjunction
• ό,τι = relative expression meaning whatever

You could say:

• Ο υπάλληλος είπε ότι εσύ δεν μπορείς να υποβάλεις ξανά την αίτηση σήμερα.

But this sounds more emphatic, as if contrasting you with someone else.

Normally Greek leaves εσύ out because μπορείς already shows you.
So the original version is the most natural neutral one:

• Ο υπάλληλος είπε ότι δεν μπορείς να υποβάλεις ξανά την αίτηση σήμερα.