A rajtkő mellett állok.

A is the definite article, equivalent to the in English.

So A rajtkő mellett állok means I am standing next to the starting block, not just next to a starting block.

A quick note:

• a is used before most consonants
• az is used before vowels

For example:

• a ház = the house
• az autó = the car

Rajtkő is a noun meaning starting block, especially the block used at the start of a swimming race.

It is a compound word:

• rajt = start
• kő = literally stone

So the literal sense is something like start-stone, but the natural meaning is starting block.

Because mellett is a postposition in Hungarian.

In English, we use a preposition before the noun:

• next to the starting block

In Hungarian, many such words come after the noun:

• a rajtkő mellett

So the structure is:

• noun + postposition

Other examples:

• az asztal alatt = under the table
• a ház előtt = in front of the house
• a szék mögött = behind the chair

Mellett means next to, beside, or by.

In this sentence, it shows location:

• a rajtkő mellett = next to the starting block

It belongs to a group of Hungarian location words/postpositions such as:

• alatt = under
• fölött/felett = above
• előtt = in front of
• mögött = behind
• mellett = beside / next to

Because Hungarian verbs usually show the subject in their ending, so the pronoun is often omitted.

Here:

• állok = I stand / I am standing

The ending -ok tells you the subject is I.

So Hungarian often leaves out én (I) unless it is needed for emphasis or contrast.

Compare:

• Állok. = I am standing.
• Én állok. = I am the one standing / I am standing (with emphasis)

Állok comes from the verb áll, meaning to stand.

Breakdown:

• áll- = verb stem
• -ok = I ending

So:

• állok = I stand / I am standing

Some present-tense forms:

• állok = I stand
• állsz = you stand
• áll = he/she/it stands
• állunk = we stand
• álltok = you plural stand
• állnak = they stand

Because Hungarian normally uses a specific verb for the physical position.

• állni = to stand
• ülni = to sit
• feküdni = to lie
• lenni / vagyok = to be

So if you want to say someone is in a standing position, Hungarian prefers áll rather than just is.

For example:

• A fiú áll. = The boy is standing.
• A fiú ott van. = The boy is there.

The second one tells location/existence, but not specifically that he is standing.

Yes, Állok a rajtkő mellett is also possible.

Hungarian word order is more flexible than English, and it often reflects focus, emphasis, or what is already known.

• A rajtkő mellett állok puts the location first, which can sound like It is next to the starting block that I am standing or simply present the setting first.
• Állok a rajtkő mellett is a more straightforward I am standing next to the starting block.

Both can be correct, but they may differ slightly in emphasis depending on context.

Because many Hungarian postpositions take the noun in its basic form, often with the article if needed.

So:

• a rajtkő mellett
• a ház előtt
• az asztal alatt

By contrast, some meanings are expressed with case endings attached directly to the noun, not with a separate postposition.

For example:

• házban = in the house
• asztalon = on the table

So in this sentence, mellett is a separate word, and rajtkő stays in its basic form.

Not exactly, though it can be similar in some contexts.

• a rajtkő mellett = next to / beside the starting block
• a rajtkőnél = at the starting block

-nál/-nél is a case ending meaning at, by, or near.

So:

• mellett is more specifically beside
• -nál/-nél is often a bit broader: at / by / near

Depending on the situation, both might be possible, but they are not always identical.

Approximately:

• rajt sounds a bit like right
• kő has a long ő, a rounded vowel that does not exist in English

A rough learner-friendly approximation might be:

• RIGHT-kuh or RIGHT-kur, but neither is exact

More importantly:

• ő is a long front rounded vowel
• it is the long version of ö

And in állok:

• á is a long vowel, somewhat like the a in father, but longer

So vowel length matters in Hungarian and should be noticed carefully.