Vinnaren och förloraren skrattar tillsammans.

Because they are in the definite singular form:

• vinnare = winner
• vinnaren = the winner
• förlorare = loser
• förloraren = the loser

In Swedish, the is usually added to the end of the noun instead of being a separate word. With many en-gender nouns that already end in a vowel, the definite ending is just -n, so:

• vinnare + n = vinnaren
• förlorare + n = förloraren

So the final -en here is not a separate word; it is part of the noun form.

The indefinite forms are:

• en vinnare = a winner
• en förlorare = a loser

So:

• Vinnaren och förloraren = the winner and the loser
• En vinnare och en förlorare = a winner and a loser

Because Swedish normally marks definiteness with a suffix on the noun.

English:

• the winner
• the loser

Swedish:

• vinnaren
• förloraren

This is a very common pattern in Swedish. English puts the before the noun, but Swedish often attaches it to the noun instead.

Skrattar is the present tense of the verb skratta, which means to laugh.

• skratta = to laugh
• skrattar = laugh / laughs / am laughing / is laughing / are laughing, depending on context

A useful point for English speakers: Swedish verbs do not change for person.

• jag skrattar = I laugh / I am laughing
• du skrattar = you laugh / you are laughing
• de skrattar = they laugh / they are laughing

The form stays skrattar.

It can mean any of those, depending on context.

Swedish usually does not make the same strong distinction that English does between:

• they laugh
• they are laughing

So Vinnaren och förloraren skrattar tillsammans could be translated naturally as either:

• The winner and the loser laugh together
• The winner and the loser are laughing together

Both are possible. Context decides which English version sounds best.

Tillsammans means together.

It is an adverb, and putting it at the end of the sentence is very natural in Swedish:

• Vinnaren och förloraren skrattar tillsammans.

That word order sounds neutral and normal. Swedish adverbs can sometimes move around, but this is a very standard placement.

Yes. Swedish is a V2 language, which means that in a main clause, the finite verb usually comes in the second position.

In your sentence:

• Vinnaren och förloraren = position 1
• skrattar = position 2

You could also move tillsammans to the front:

• Tillsammans skrattar vinnaren och förloraren.

That still means basically the same thing, but it gives a little more emphasis to together.

Yes. They are connected to the verbs:

• vinna = to win
• förlora = to lose

From those, you get:

• vinnare = winner
• förlorare = loser

The ending -are is a common way to form a noun meaning a person who does something, similar to English -er in words like winner or runner.

A rough guide is:

• vinnaren ≈ VIN-na-ren
• förloraren ≈ fur-LO-ra-ren
• skrattar ≈ SKRAT-tar
• tillsammans ≈ til-SAM-mans

A few helpful notes:

• sk in skrattar sounds much like the sk in English screen
• ä in skrattar is somewhat similar to the vowel in cat, though not exactly the same
• ö in förloraren does not have an exact English equivalent, so it often takes practice

These rough spellings are only approximate, but they can help you get started.