pegu ha koko ni aru.

ペグ is written in katakana because it is a loanword, probably borrowed from English peg.

In Japanese:

• hiragana is mainly used for native grammar words and some native words
• katakana is often used for foreign loanwords, sound effects, and emphasis
• kanji is used for many native and Sino-Japanese words

So ペグ being in katakana signals that it is not a traditional native Japanese word.

は marks ペグ as the topic of the sentence.

So ペグは means something like:

• as for the peg,
• the peg

This does not always match English subject exactly. The topic is what the sentence is about.

So:

ペグは ここに ある。
= As for the peg, it is here.

The sentence is telling you where the peg is.

This is one of the special cases in Japanese.

The hiragana は is normally read ha, but when it is used as the topic particle, it is pronounced wa.

So in this sentence, you read it as:

ペグ は ここ に ある
→ pegu wa koko ni aru

Not pegu ha.

ここ is a place word, meaning here.

Japanese has a common set of location words:

• ここ = here
• そこ = there near you
• あそこ = over there
• どこ = where

In this sentence, ここ is the location being pointed out.

に marks the location where something exists or is located.

With verbs like:

• ある = to exist, to be (for things)
• いる = to exist, to be (for people/animals)

the place is usually marked by に.

So:

• ここにある = is here
• literally, exists at here

This is different from で, which usually marks the place where an action happens.

Compare:

• ここにある = it is here
• ここで食べる = eat here

Japanese usually uses:

• ある for things and inanimate objects
• いる for people and animals

A peg is an object, so ある is the correct verb.

Examples:

• 本がある。 = There is a book.
• 猫がいる。 = There is a cat.

So ペグはここにある。 is natural because a peg is not a living thing.

It can function as both, depending on how it is translated into natural English.

ある literally has the sense of exist / be present / be located for things.

So this sentence could be understood as:

• The peg is here.
• There is a peg here.

The exact English wording depends on context, but the Japanese verb is the same basic verb: ある.

Because ペグ is already marked as the topic with は.

Japanese often uses either:

• X は ... to introduce the topic, or
• X が ... to mark the grammatical subject more directly

Here, ペグは means the sentence is talking about the peg specifically.

A sentence with が would feel a bit different:

• ペグがここにある。 = There is a peg here / The peg is here
• ペグはここにある。 = As for the peg, it is here

Very roughly:

• が can sound more like presenting new information
• は can sound more like talking about something already known or contrasting it with something else

Yes, Japanese word order is more flexible than English, as long as the particles make the roles clear.

For example, these can all be understandable:

• ペグはここにある。
• ここにペグはある。

However, the most neutral version here is ペグはここにある。

Japanese often puts the verb at the end, but elements before the verb can sometimes move around for emphasis or style.

It is in the plain form because the verb is ある.

A polite version would be:

ペグはここにあります。

So:

• ある = plain
• あります = polite

You might use:

• ある in casual speech, narration, notes, or informal writing
• あります when speaking politely

The spaces are almost certainly just for learners.

Normal Japanese writing would usually be:

ペグはここにある。

Japanese does not normally use spaces between words the way English does. Teaching materials often add spaces to make the sentence structure easier to see.

It is pronounced roughly:

pegu wa koko ni aru

A very rough English-style guide:

• ペグ = peh-goo (though the final u is light)
• は = wa
• ここ = ko-ko
• に = nee
• ある = a-ru

A more natural rhythm is:

pegu wa koko ni aru

with the verb ある coming clearly at the end.