Der Startspieler stellt die Spielfigur auf den Spielplan.

Because aufstellen is a separable verb in German.

• The full infinitive is aufstellen = to place / set / put upright / put onto
• In a normal present-tense main clause, the verb splits:
  • stellt goes to the usual verb position
  • auf goes to the end

So:

• Der Startspieler stellt die Spielfigur auf den Spielplan auf.

However, in your sentence, auf is followed directly by den Spielplan, so what you are really seeing is:

• stellt ... auf den Spielplan

Here auf belongs both to the separable verb idea and also introduces the destination phrase. This is very natural in German with verbs of placing.

A learner should mainly recognize:

• aufstellen = the dictionary form
• stellt ... auf = the conjugated form in the sentence

Because Der Startspieler is the subject of the sentence — the person doing the action.

German marks the subject with the nominative case.

• der = nominative masculine singular
• Startspieler is masculine, so it takes der here

In English, we usually identify the subject mostly by word order. In German, word order helps too, but the article also shows the grammatical role.

Here:

• Der Startspieler = the starting player
• This is the one who places the game piece

Because Spielfigur is a feminine noun, so in the accusative singular it still takes die.

Here die Spielfigur is the direct object — the thing being placed.

Cases here:

• Der Startspieler = nominative subject
• die Spielfigur = accusative direct object

For feminine nouns, the article is:

• nominative: die
• accusative: die

So the form does not change, even though the function changes.

Because the sentence describes movement to a destination, not a static location.

The preposition auf is a two-way preposition (Wechselpräposition). That means:

• accusative = movement toward a place
• dative = location in/on a place

So:

• auf den Spielplan = onto the board / to the board → movement, so accusative
• auf dem Spielplan = on the board → location, so dative

Compare:

• Der Startspieler stellt die Spielfigur auf den Spielplan.
  • The piece is being moved onto the board.
• Die Spielfigur steht auf dem Spielplan.
  • The piece is on the board.

stellt is the 3rd person singular present tense form of stellen or, in this sentence, the separable verb aufstellen.

Here it means something like:

• places
• sets
• puts

More literally, stellen often suggests putting something in an upright position, but in many contexts it is simply the normal verb for placing an object somewhere.

Because this is a board-game sentence, a natural English translation is often:

• The starting player places the game piece on the board.

German often uses auf for both on and onto, and the case tells you whether it means location or motion.

So English makes the distinction with different words:

• on = location
• onto = movement

German often makes the distinction like this:

• auf dem Spielplan = on the board
• auf den Spielplan = onto the board

So the article changes, not necessarily the preposition itself.

Yes. Startspieler is a compound noun:

• Start = start
• Spieler = player

Together:

• Startspieler = starting player / first player

German very often combines nouns into one word where English would use two or more words.

Other examples:

• Spielplan = game board / board layout
• Spielfigur = game piece / playing figure

This is extremely common and important in German vocabulary.

Den Spielplan is the destination of the movement.

The game piece is being placed:

• on/onto the board

Grammatically:

• auf is the preposition
• den Spielplan is its object
• because there is motion toward a destination, it is in the accusative

So the sentence has:

• subject: Der Startspieler
• direct object: die Spielfigur
• prepositional phrase showing destination: auf den Spielplan

German main clauses normally put the conjugated verb in the second position.

So the structure is:

• Der Startspieler = first element
• stellt = conjugated verb in second position
• then the rest of the sentence follows

A useful breakdown is:

• Subject: Der Startspieler
• Verb: stellt
• Object: die Spielfigur
• Destination phrase: auf den Spielplan

This is a very normal and natural word order in German.

Yes. German allows some flexibility, as long as the finite verb stays in second position in a main clause.

For example:

• Die Spielfigur stellt der Startspieler auf den Spielplan.
• Auf den Spielplan stellt der Startspieler die Spielfigur.

These versions are possible, but they change the emphasis. The original sentence is the most neutral and straightforward.

For learners, the important rule is:

• in a main clause, the conjugated verb usually stays in position 2

They can overlap, but they are not always exactly the same.

• Brett = board, plank
• Spielbrett = game board
• Spielplan = game board / playing board / layout of a game, often especially the printed board or play area

In many board-game contexts, Spielplan is a very natural choice for the board you place pieces on.

So in this sentence:

• auf den Spielplan = onto the game board

Because the case marking here is mostly shown by the article, not by the noun itself.

Look at the noun phrases:

• Der Startspieler
• den Spielplan

The masculine articles change:

• nominative: der
• accusative: den

But the noun often stays the same:

• Startspieler
• Spielplan

This is very common in German, especially with singular nouns. The article often gives you the clearest clue about the case.

Usually it refers to a playing piece, often a small figure, token, pawn, or character piece used in a game.

Depending on the game, English might translate it as:

• game piece
• playing piece
• token
• figure
• pawn

So even if the German word literally contains Figur, the best English translation depends on the game context.