Jag måste ställa kannan på bordet innan gästerna kommer.

Because in Swedish, modal verbs like måste are followed directly by the infinitive, with no att.

• Jag måste ställa kannan ... = I must put the jug ...
• Compare:
  • Jag vill gå. = I want to go.
  • Jag kan komma. = I can come.

So after måste, you normally just use the base infinitive form: ställa.

Swedish often chooses different verbs depending on the position an object ends up in.

• ställa = put something so that it ends up standing
• lägga = put something so that it ends up lying
• sätta = set/put, often used for a person sitting, or in some fixed expressions
• placera = place/position, more formal or neutral

A jug or pitcher typically stands upright on a table, so ställa is the natural choice:

• ställa kannan på bordet

If it were, for example, a book, Swedish would more naturally use lägga:

• lägga boken på bordet

This is a very Swedish way of thinking about placement, and it often feels more specific than English put.

Because kannan is the definite form: the jug / the pitcher.

• en kanna = a jug
• kannan = the jug

In Swedish, definiteness is usually added as an ending on the noun:

• en kanna → kannan
• ett bord → bordet

So Jag måste ställa kannan på bordet means I must put the jug on the table, not a jug on a table.

For the same reason: bordet is the definite form, meaning the table.

• ett bord = a table
• bordet = the table

Swedish uses a suffix to mark the, instead of a separate word like English usually does.

So:

• på bordet = on the table
• på ett bord = on a table

Because Swedish nouns belong to different grammatical genders.

• kanna is a common gender noun (en word):

  • en kanna
  • kannan

• bord is a neuter noun (ett word):

  • ett bord
  • bordet

A very simplified pattern is:

• en-word definite singular often ends in -en or -n
• ett-word definite singular often ends in -et or -t

So the endings depend on the noun type.

Gästerna is the definite plural form of gäst.

• en gäst = a guest
• gäster = guests
• gästerna = the guests

So:

• innan gästerna kommer = before the guests come / before the guests arrive

Again, Swedish marks definiteness mainly with endings.

Because Swedish often uses the present tense for future events when the context already makes the future meaning clear.

Here, innan and the situation make it obvious that this is about something that will happen later:

• innan gästerna kommer = before the guests come / before the guests arrive

This is very common in Swedish.

Compare:

• Jag ringer dig i morgon. = I’ll call you tomorrow.
• Vi åker nästa vecka. = We’re leaving next week.

So kommer here is grammatically present, but naturally understood as future.

Innan means before and introduces a time clause.

The sentence is divided like this:

• Jag måste ställa kannan på bordet
• innan gästerna kommer

So the second part tells you before when the action must happen.

Innan can be followed by:

• a clause: innan gästerna kommer
• sometimes just a noun phrase in other contexts

Here it introduces a full clause with subject + verb.

Because after innan, Swedish uses subordinate clause word order, where the subject normally comes before the verb.

So:

• innan gästerna kommer

not

• innan kommer gästerna

This is standard Swedish subordinate clause structure.

A good thing to notice is that in a normal subordinate clause, Swedish does not invert the subject and verb the way it often does in main clauses.

It can often be understood as either, depending on context.

• literal/basic meaning: come
• very natural translation here: arrive

So innan gästerna kommer can be translated as:

• before the guests come
• before the guests arrive

In everyday English, arrive may sound slightly more natural here, but Swedish simply uses kommer.

Usually, that would sound less natural.

Lägga suggests putting something down so it ends up lying flat. A jug normally stands upright, so Swedish prefers ställa.

• natural: ställa kannan på bordet
• less natural in normal context: lägga kannan på bordet

If you deliberately meant laying the jug on its side, then lägga could make sense.

Because Swedish usually attaches definiteness directly to the noun instead of using a separate article.

English:

• the jug
• the table
• the guests

Swedish:

• kannan
• bordet
• gästerna

So the meaning of the is already built into the endings.

Here are the base forms:

• jag = I
• måste = from måste / modal verb, usually listed as måste (it doesn’t behave like a regular infinitive verb in everyday use)
• ställa = to place / to set / to put standing
• kannan → base form kanna
• bordet → base form bord
• innan = before
• gästerna → base form gäst
• kommer → infinitive komma

This is useful because Swedish dictionary lookup is usually done with the base noun or infinitive verb.

Yes. Måste can often be translated as must or have to, depending on what sounds most natural in English.

So all of these can work:

• I must put the jug on the table before the guests come.
• I have to put the jug on the table before the guests arrive.
• I need to put the jug on the table before the guests come.

The exact English choice depends on style and context, but the Swedish grammar stays the same.