Spelarna är här allihop.

Because -na is the definite plural ending.

• spelare = player / players (the singular and plural forms are the same)
• spelarna = the players

So spelarna does not just mean players in general. It means a specific group: the players.

Yes. Spelare is one of many Swedish nouns that have the same form in the singular and plural indefinite.

• en spelare = a player
• spelare = players
• spelaren = the player
• spelarna = the players

This is very common with nouns ending in -are, such as:

• en lärare = a teacher
• lärare = teachers
• läraren = the teacher
• lärarna = the teachers

Är is the present tense of vara, which means to be.

So:

• är = is / are / am, depending on the subject in English

Swedish does not change the verb depending on the person the way English does.

For example:

• Jag är här = I am here
• Du är här = You are here
• Spelarna är här = The players are here

The form är stays the same.

That is the normal word order in a simple Swedish statement:

subject + verb + adverb/place expression

So:

• Spelarna = subject
• är = verb
• här = place expression

This gives the very standard pattern:

• Spelarna är här = The players are here

Then allihop is added at the end for emphasis or completeness.

Allihop means all of them, all together, or simply everyone/everything in the group, depending on context.

In this sentence, it emphasizes that the whole group is present:

• Spelarna är här allihop = The players are all here / The players are all here, every one of them

It often has a slightly conversational, natural feel.

Putting allihop at the end is very natural in Swedish. It adds the idea of every single one after the basic statement.

Compare:

• Spelarna är här = The players are here
• Spelarna är här allihop = The players are here, all of them

The final allihop gives extra emphasis to the completeness of the group.

Yes. That is also correct, but it is structured differently.

• Alla spelarna är här = All the players are here
• Spelarna är här allihop = The players are here, all of them

The difference is mostly one of style and focus:

• Alla spelarna är här puts all before the noun phrase.
• Spelarna är här allihop starts with the players and then adds all of them at the end.

Both are natural. The second can sound a bit more conversational or emphatic.

They are similar, but not always used in exactly the same way.

alla

Usually means all or everyone.

• Alla spelarna är här = All the players are here
• Alla är här = Everyone is here

allihop

Often means all of them or everyone, with a slightly spoken, everyday feel.

• Ni är här allihop = You are all here
• Spelarna är här allihop = The players are here, all of them

allesammans

Also means all of you / all of them / everyone together, often a bit more explicit or slightly more formal than allihop, though both are common.

• Ni är här allesammans
• Spelarna är här allesammans

In many everyday contexts, allihop and allesammans can replace each other.

Yes. Because it is definite plural, it refers to a specific group already known from the situation or earlier context.

So spelarna is more like:

• the players
• those players
• the players we are talking about

If you wanted a more general sense, you would use spelare without the definite ending:

• Spelare är ofta trötta efter matchen = Players are often tired after the match

That is a general statement about players.

It is most commonly used with people, but it can also be used more broadly for things in a group.

For example:

• Barnen kom allihop = The children all came
• Böckerna låg där allihop = The books were all lying there

Still, with people it is especially common and natural.

A careful pronunciation would be roughly:

Spelarna är här allihop

Some useful points:

• spelarna has stress on the first syllable: SPE-lar-na
• är is pronounced like a vowel sound somewhat similar to air in many English accents, but not exactly
• här sounds similar to är, but with an h at the start
• allihop usually has the main stress on the last part: alli-HOP

In natural speech, är här may run together a bit smoothly.

It sounds very natural and everyday.

The sentence is completely correct, but allihop gives it a spoken, conversational feel. It is the kind of thing someone might naturally say when checking whether everyone has arrived.

A slightly more neutral or formal version might be:

• Alla spelarna är här
• Samtliga spelare är här (more formal, less everyday)

So the original sentence is natural, correct, and common in ordinary speech.