Leikpeðið er á fyrsta reitnum.

A natural breakdown is:

• Leikpeðið = the game piece / the playing piece
• er = is
• á = on
• fyrsta = first
• reitnum = the square / the space / the cell, in a case form used after á

So the structure is basically:

Leikpeðið + er + á fyrsta reitnum
The game piece + is + on the first square

This is a very normal Icelandic sentence pattern: subject + verb + prepositional phrase.

Because -ið is the definite article attached to the noun.

• leikpeð = game piece
• leikpeðið = the game piece

In Icelandic, the word for the is often added to the end of the noun instead of standing separately in front of it.

That is one of the first big differences from English:

• English: the game piece
• Icelandic: leikpeð + ið = leikpeðið

So leikpeðið is a neuter singular noun with the definite article attached.

Er is the present-tense form of vera, which means to be.

So here:

• leikpeðið er = the game piece is

It is the same verb you use in many basic Icelandic sentences:

• Hann er hér. = He is here.
• Hún er góð. = She is good.
• Þetta er bók. = This is a book.

So in your sentence, er is simply the verb is.

Á often means on.

In this sentence, it tells you where the game piece is located:

• á fyrsta reitnum = on the first square

A very useful thing to know is that á can be used both for:

• location: on
• movement onto something: onto

The case often helps show the difference:

• á fyrsta reitnum = on the first square → location
• á fyrsta reit / another accusative form in context = onto the first square → movement toward

So here, because the piece is already there, á means on in a location sense.

Because á takes the dative case when it describes location.

The basic noun is:

• reitur = square, space, cell

But after á in a static location meaning, Icelandic uses the dative:

• á reitnum = on the square

So:

• reitur = nominative, the basic dictionary form
• reitnum = dative singular definite, the form needed here

This is a very common Icelandic pattern:

• í húsinu = in the house
• á borðinu = on the table
• á reitnum = on the square

So reitnum is there because the preposition and the meaning of location require that form.

It does change — and fyrsta is the changed form.

Fyrsti / fyrsta / fyrsta is the ordinal adjective first, and like adjectives in Icelandic, it must agree with the noun it describes.

Here it goes with reitnum, which is:

• masculine
• singular
• dative
• definite

With that kind of noun, the correct weak form of fyrstur is fyrsta.

So:

• fyrsti reitur = first square (basic indefinite kind of form)
• á fyrsta reitnum = on the first square (dative after á, with definite noun)

The important learner takeaway is: adjectives and ordinals change form to match the noun’s gender, number, case, and often definiteness.

Because that is a normal Icelandic way of making noun phrases definite.

English says:

• the first square

Icelandic often does this instead:

• adjective/ordinal + noun with attached article
• fyrsta reitnum

So the definiteness is shown on the noun itself, not by a separate word in front.

This is very common:

• gamla húsið = the old house
• fyrsta reitnum = the first square (in this case form)

So even though there is no separate word exactly like English the in front of first, the whole phrase is still definite.

The given order is the most straightforward one:

• Leikpeðið er á fyrsta reitnum.

That is the normal neutral order: subject + verb + location.

But Icelandic can move things around for emphasis. For example:

• Á fyrsta reitnum er leikpeðið.

This can sound more like:

• On the first square is the game piece
• or more naturally, The game piece is on the first square, but with extra focus on the location

So the original sentence is the best default pattern for learners, but other word orders are possible.

A rough learner-friendly guide would be:

• Leikpeðið ≈ LAYK-peth-ith
• er ≈ ehr
• á ≈ ow as in cow, but longer
• fyrsta ≈ FIR-sta
• reitnum ≈ RAYT-num

A few helpful notes:

• ei in Icelandic often sounds like ay in day
• ð is like a soft th sound, as in this
• á is a long vowel
• y in Icelandic does not sound exactly like English y; in fyrsta, English speakers often approximate it with i at first

So a rough full pronunciation is:

LAYK-peth-ith ehr ow FIR-sta RAYT-num

That is only an approximation, but it is a useful starting point.

No. Icelandic does not capitalize all nouns the way German does.

Leikpeðið is capitalized here only because it is the first word of the sentence.

So:

• Leikpeðið er á fyrsta reitnum.
• but in the middle of a sentence: Ég sé leikpeðið. = I see the game piece.

Only proper names and normal sentence-initial capitalization are used, not general noun capitalization.