yamahuda wo banmen ni oku.

It follows a very common Japanese pattern:

[thing] を [place] に [verb]

So here:

• 山札 = the deck
• を = marks the thing being acted on
• 盤面 = the board / play area surface
• に = marks the destination or resulting location
• 置く = to place / put

So the sentence is literally something like:

[The deck] [object marker] [on/to the board surface] [place]

Natural English: Place the deck on the board.

を marks the direct object of the verb.

In this sentence, 山札 is the thing being placed, so it takes を:

• 山札を置く = place the deck

Even though English uses place X on Y, Japanese still marks X with を because X is what the action directly affects.

This is a very common learner question.

Here, に marks the destination or resulting location of the action:

• 盤面に置く = put it onto / in the position of the board

With verbs like 置く, に is used because the object ends up in that location.

By contrast, で usually marks the place where an action happens, especially an activity:

• 教室で勉強する = study in the classroom

For putting something somewhere, に is the normal choice:

• 机に本を置く = put a book on the desk

Japanese often leaves out the subject when it is obvious from context.

In a game rule, instruction, or manual, the understood subject is often:

• you
• the player
• or just an impersonal one should

So 山札を盤面に置く can function like:

• Place the deck on the board
• You place the deck on the board

Japanese does this very naturally, while English usually needs an explicit subject or imperative form.

The dictionary form is very common in:

• instructions
• manuals
• rulebooks
• captions
• simple procedural steps

So 山札を盤面に置く has a concise, instruction-like feel.

Compare:

• 山札を盤面に置く = plain, neutral, rule/instruction style
• 山札を盤面に置いてください = please place the deck on the board
• 山札を盤面に置きます = polite statement, less typical for short rule text

In game rules, the plain form is extremely common.

These are both game-related words.

• 山札 (やまふだ) literally contains 山, meaning mountain, because a stack of cards looks like a little pile or mound. In games, it usually means the deck or draw pile.
• 盤面 (ばんめん) means the surface of the board, the board state, or the play area on the board.

So this sentence sounds like game instructions, not everyday conversation.

The readings are:

• 山札 = やまふだ
• を = pronounced o
• 盤面 = ばんめん
• に = ni
• 置く = おく

So the whole sentence is read:

やまふだ を ばんめん に おく。

Yes, to some extent.

Because Japanese uses particles, the roles of the words are marked clearly, so you can also say:

• 盤面に山札を置く。

This means the same thing.

That said, some orders sound more natural depending on context. Both are understandable, but 盤面に山札を置く may sound a little more standard because the location phrase often comes before the object-verb combination.

Still, the original order is perfectly possible.

Yes. Japanese に does not always translate neatly as just to.

It marks the location where something exists or ends up. With 置く, that often corresponds to English on, in, or at, depending on the noun.

Examples:

• 机に本を置く = put a book on the desk
• 箱に本を置く = put a book in the box
• そこに置く = put it there

So in this sentence, 盤面に is naturally on the board.

Yes, 置く is a very common verb meaning to put, to place, or to set down.

It often implies placing something somewhere and leaving it there.

In game instructions, 置く is a standard choice for physically placing a card, token, piece, or deck onto the play area.

So 山札を盤面に置く sounds very natural for a rule like:

• place the deck on the board
• set the deck on the play area

It sounds most natural as:

• a rulebook instruction
• a manual step
• a note in a game
• a brief procedural description

In everyday conversation, people might use a fuller form depending on the situation, such as:

• 山札を盤面に置いて。 = Put the deck on the board.
• 山札を盤面に置いてください。 = Please put the deck on the board.
• 山札を盤面に置くんだよ。 = You put the deck on the board, okay?

So the plain form by itself is natural, but it has a concise, instructional feel.