De olifant loopt langzaam.

Because olifant is a de-word in Dutch. Nouns in Dutch take either de or het as their definite article, and this is something you usually have to learn with each noun.

So:

• de olifant = the elephant
• het huis = the house

There is not always a simple rule you can rely on, so it is best to learn nouns together with their article.

Loopt is the conjugated form of the verb lopen (to walk / to run, depending on context).

In this sentence, the subject is de olifant, which is third person singular, so Dutch uses the present-tense form loopt.

Present tense of lopen:

• ik loop = I walk
• jij loopt = you walk
• hij/zij/het loopt = he/she/it walks
• wij lopen = we walk
• jullie lopen = you walk
• zij lopen = they walk

So de olifant loopt literally matches the elephant walks.

In the present tense, Dutch usually adds -t for second person singular and third person singular.

Here, de olifant is a singular subject, so you get:

• stem: loop
• third person singular: loopt

That -t is very common in Dutch verbs:

• hij werkt = he works
• de kat slaapt = the cat sleeps
• de olifant loopt = the elephant walks

Here it is an adverb, because it describes how the elephant walks.

• De olifant is langzaam.
  Here langzaam is an adjective meaning slow.

• De olifant loopt langzaam.
  Here langzaam is an adverb meaning slowly.

A useful thing for English speakers: Dutch often uses the same form for both adjective and adverb. English usually changes slow to slowly, but Dutch often does not make that change.

Because Dutch usually does not form adverbs by adding something like English -ly.

So:

• langzaam = slow
• langzaam = slowly

The form stays the same. This is very normal in Dutch.

Other examples:

• een hard geluid = a loud sound
• hij praat hard = he speaks loudly

So English often changes the form, but Dutch often doesn’t.

This follows normal Dutch main-clause word order:

1. subject: De olifant
2. finite verb: loopt
3. other information: langzaam

A very important Dutch rule is that in a normal main clause, the finite verb usually comes in the second position.

So this sentence is structured very naturally:

• De olifant = subject
• loopt = verb
• langzaam = adverb

Compare:

• De olifant loopt langzaam.
• Vandaag loopt de olifant langzaam.

In the second example, vandaag comes first, but loopt still stays in second position.

Yes, sometimes, but De olifant loopt langzaam is the most straightforward and natural basic order.

You may also see things like:

• Langzaam loopt de olifant.

This is possible, but it sounds more marked or stylistic, as if you are emphasizing slowly.

In a subordinate clause, the order changes:

• Ik zie dat de olifant langzaam loopt.
  = I see that the elephant walks slowly.

So the position of langzaam can vary, but in a simple statement, after the verb is a very common place.

A helpful rough guide is:

• loopt sounds approximately like lope-t, but with the oo as one long vowel, not two separate sounds.

A few points:

• oo is a long vowel
• the p is clearly pronounced
• the final t is also pronounced

So it is not like English looped. It is closer to lope-t, but with Dutch vowel quality.

Not always. Lopen can mean several related things, depending on context.

Common meanings include:

• to walk
• to go on foot
• sometimes to run in certain expressions or contexts
• for things like machines or processes, sometimes to run or to operate

In De olifant loopt langzaam, the most natural meaning is The elephant walks slowly.

Yes. That would mean An elephant walks slowly.

The difference is the article:

• de olifant = the elephant
• een olifant = an elephant

So both are grammatically correct, but they mean different things.

Dutch often uses the simple present where English might use either the simple present or the present continuous.

So:

• De olifant loopt langzaam.
  can often correspond to
  The elephant walks slowly
  or, depending on context, The elephant is walking slowly.

If Dutch really wants to emphasize an ongoing action, it can use another construction, for example:

• De olifant is langzaam aan het lopen.

But in many everyday situations, plain loopt is enough.