Leikurinn í kvöld er uppseldur.

Leikurinn means the game/match/play, while leikur means a game/match/play.

Icelandic usually adds the definite article to the end of the noun, instead of using a separate word like English the.

• leikur = a game
• leikurinn = the game

So Leikurinn í kvöld means the game tonight or tonight’s game, not just a game tonight.

Í kvöld means tonight.

Literally, it is related to in the evening, but in normal Icelandic it is a very common time expression meaning tonight.

So:

• í kvöld = tonight
• í morgun = this morning
• í gær = yesterday

In this sentence, í kvöld tells you which game is being talked about: the game tonight.

Because uppseldur agrees with leikurinn.

The noun leikurinn is:

• masculine
• singular
• nominative

So the word describing it also has to be masculine singular nominative:

• uppseldur = masculine singular
• uppseld = feminine singular
• uppselt = neuter singular
• uppseldir = masculine plural

Examples:

• Leikurinn er uppseldur. = The game is sold out.
• Sýningin er uppseld. = The show is sold out.
• Mótið er uppselt. = The tournament/event is sold out.
• Tónleikarnir eru uppseldir. = The concerts are sold out.

It is originally a past participle of the verb að selja upp / að vera uppseldur in this kind of usage, but in sentences like this it behaves very much like an adjective.

That is why it changes form for gender, number, and case, just like an adjective.

So in Leikurinn í kvöld er uppseldur, the meaning is basically:

• The game tonight is sold out.

It describes the current state of the game/event: there are no tickets left.

Because í kvöld is most naturally attached to leikurinn here:

• Leikurinn í kvöld = the game tonight

So the sentence groups like this:

• [Leikurinn í kvöld] er uppseldur
• [The game tonight] is sold out

If you say Leikurinn er uppseldur í kvöld, it can sound more like the game is sold out tonight, where tonight modifies the whole statement rather than identifying which game you mean. That is usually less natural if your main point is tonight’s game.

Yes, potentially.

The noun leikur can mean different things depending on context, such as:

• game
• match
• play
• sometimes more broadly performance in certain contexts

So Leikurinn í kvöld er uppseldur could refer to a sports game, a theatrical performance, or something similar. You need context to know which one.

Er is the present tense of að vera = to be.

So:

• er = is

The structure is very straightforward:

• Leikurinn í kvöld = the game tonight
• er = is
• uppseldur = sold out

So word-for-word, it is:

• The-game tonight is sold-out

It is in the nominative singular.

That is because it is the subject of the sentence:

• Leikurinn í kvöld = the subject
• er uppseldur = what is being said about the subject

You can see the nominative singular definite ending in -inn here:

• leikur = nominative singular indefinite
• leikurinn = nominative singular definite

In í kvöld, learners often notice that í can take different cases in Icelandic. Here, though, the most important thing is to learn í kvöld as a fixed time expression meaning tonight.

Because kvöld is a neuter noun, its nominative and accusative singular look the same:

• kvöld = nominative/accusative singular
• kvöldi = dative singular

So from the form alone, you do not see a difference here. For practical purposes, it is best to memorize í kvöld as one common phrase.

A rough pronunciation guide for English speakers is:

LAY-ku-rinn ee KHVUHLD ehr UP-sel-dur

A few notes:

• ei in leikurinn sounds roughly like ay
• í is a long ee
• kv in kvöld is pronounced with a noticeable k
  • v sound
• ö does not exist in English; it is somewhat like the vowel in some versions of bird, but shorter and rounder
• ll in seldur is just a normal l, but in some Icelandic words ll can have a special pronunciation, so learners often watch for that

If you want a simpler learner-friendly rhythm, you can think of it as:

LEI-ku-rinn | í kvöld | er upp-seldur

The main change would be the form of uppseldur, because it has to agree with the noun.

Examples:

• Sýningin í kvöld er uppseld.
  The show tonight is sold out.
  (sýningin is feminine singular)

• Mótið í kvöld er uppselt.
  The event/tournament tonight is sold out.
  (mótið is neuter singular)

• Tónleikarnir í kvöld eru uppseldir.
  The concerts tonight are sold out.
  (tónleikarnir is masculine plural, and er becomes eru)

So this sentence is a good example of how Icelandic agreement works across the whole clause.

Yes, it is completely natural.

It is a normal way to say that tonight’s event has no tickets left. Depending on context, people might also say similar things like:

• Það er uppselt á leikinn í kvöld. = It is sold out for the game tonight.
• Leikurinn er uppseldur. = The game is sold out.
• Það er orðið uppselt í kvöld. = It has become sold out tonight / Tonight is sold out.

But Leikurinn í kvöld er uppseldur is clear, idiomatic, and very natural.