Vanaf morgen oefenen wij elke dag Nederlands.

Vanaf marks a starting point that continues onward. So vanaf morgen means starting tomorrow, from tomorrow on, or as of tomorrow.

It is a little more specific than just morgen, because it emphasizes the beginning of a new routine or period.

This is because Dutch main clauses usually follow the verb-second rule.

In this sentence, Vanaf morgen is placed first for emphasis. Once that first element takes the first position, the finite verb must come next:

• Vanaf morgen = first position
• oefenen = second position
• wij = subject after the verb

So:

• Wij oefenen elke dag Nederlands.
• Vanaf morgen oefenen wij elke dag Nederlands.

Both are correct, but the second one emphasizes starting tomorrow.

Both wij and we mean we.

The difference is mainly style and stress:

• we is more common in everyday speech and informal writing
• wij is a bit more formal or more emphatic

So this sentence could also be:

• Vanaf morgen oefenen we elke dag Nederlands.

That would sound very natural too.

Because wij takes the plural present-tense form of the verb.

The verb is oefenen = to practise.
In the present tense:

• ik oefen
• jij oefent
• hij/zij oefent
• wij oefenen
• jullie oefenen
• zij oefenen

So wij oefenen means we practise.

It happens to look the same as the infinitive, which is very common in Dutch plural present forms.

Dutch often uses the present tense for the future when a time expression already makes the future clear.

Here, vanaf morgen already tells you that the action starts in the future, so there is no need for a special future form.

That is very similar to English sentences like:

• Tomorrow we start
• Next week I work from home

Dutch could also use a future construction, for example:

• Vanaf morgen gaan wij elke dag Nederlands oefenen.

But the simple present is very normal and natural here.

When a language is the object of verbs like leren (learn), spreken (speak), or oefenen (practise), Dutch often uses the language name without an article:

• Ik leer Nederlands.
• Zij spreekt Engels.
• Wij oefenen Nederlands.

If you say het Nederlands, you are talking about the Dutch language as a thing or concept:

• Het Nederlands is niet makkelijk.

So in your sentence, bare Nederlands is the normal choice.

Because Nederlands is the direct object of oefenen.

In other words, you are practising Dutch itself, so no preposition is needed:

• Wij oefenen Nederlands.

If you said in het Nederlands, that would mean in Dutch, which is different:

• Wij oefenen in het Nederlands. = We practise in Dutch.
• Wij oefenen Nederlands. = We practise Dutch.

So the sentence is not missing anything; it is using the normal object pattern.

In standard Dutch, the names of languages are written with a capital letter:

• Nederlands
• Engels
• Duits
• Frans

So Nederlands is capitalized because it is the name of the language.

Elke dag is a time expression meaning every day. In Dutch, expressions of time often come after the subject and before the object or other information.

So this order is very natural:

• Vanaf morgen oefenen wij elke dag Nederlands.

You may also see other word orders, but they can shift the emphasis:

• Wij oefenen vanaf morgen elke dag Nederlands.
• Wij oefenen elke dag Nederlands vanaf morgen.
  This last one is much less natural in most contexts.

So the original sentence has a very normal, smooth Dutch word order.

Yes. Elke dag and iedere dag both mean every day.

In most everyday contexts, they are interchangeable:

• Vanaf morgen oefenen wij elke dag Nederlands.
• Vanaf morgen oefenen wij iedere dag Nederlands.

Sometimes iedere can sound a little more like each and every, but in practice both are common and correct.

They are related, but not the same:

• oefenen = to practise
• leren = to learn
• studeren = to study

So:

• Wij oefenen Nederlands. = We practise Dutch.
• Wij leren Nederlands. = We are learning Dutch.
• Wij studeren Nederlands. = We study Dutch.

With languages, oefenen suggests that you already know at least some Dutch and are working on improving it through practice.