Dekktrykket er lavt, så bruk sykkelpumpen.

Because Norwegian usually writes compound nouns as a single word.

dekktrykket breaks down like this:

• dekk = tire
• trykk = pressure
• -et = the definite ending for a neuter singular noun

So dekktrykket literally means the tire pressure.

In Norwegian, the is often built into the end of the noun instead of being a separate word.

So:

• et dekktrykk = a tire pressure
• dekktrykket = the tire pressure

This is very common in Norwegian.

Because lavt agrees with the noun dekktrykket, which is neuter singular.

The base adjective is lav = low, but it changes depending on gender and number:

• lav for many common-gender singular nouns
• lavt for neuter singular nouns
• lave for plural

Since dekktrykk is a neuter noun, you get Dekktrykket er lavt.

Here så means so, therefore, or as a result.

It connects the two ideas:

• the tire pressure is low
• therefore, use the bicycle pump

So it is not just a time word like then here; it shows consequence.

Bruk is the imperative form of the verb å bruke = to use.

So:

• å bruke = to use
• bruk! = use!

In this sentence, bruk sykkelpumpen means use the bicycle pump.

Because Norwegian imperatives usually do not include the subject.

Just like in English:

• Use the bicycle pump. not usually
• You use the bicycle pump.

So bruk by itself is a normal command or instruction.

Sykkelpumpen means the bicycle pump, while en sykkelpumpe means a bicycle pump.

The definite form suggests a specific pump:

• maybe the one nearby
• maybe the one the listener already knows about
• maybe the one normally used for bikes

If you said bruk en sykkelpumpe, that would sound more like use any bicycle pump.

Yes. It is another Norwegian compound:

• sykkel = bicycle
• pumpe = pump
• -n / -en = the definite ending

So sykkelpumpen means the bicycle pump.

This is very typical Norwegian word-building: smaller words combine into one longer noun.

Not necessarily. In Norwegian, the imperative is often used in a neutral, practical way, especially for:

• instructions
• advice
• warnings
• signs
• manuals

So Dekktrykket er lavt, så bruk sykkelpumpen sounds like a straightforward instruction or recommendation, not automatically rude.

The comma separates two clauses:

• Dekktrykket er lavt
• så bruk sykkelpumpen

It helps show the pause between the reason and the result. In a sentence like this, the comma is natural and makes the structure clearer.

It works for both, depending on context.

Lav / lavt / lave can mean:

• low in height or position
• low in amount or level
• low in pressure

Here it clearly refers to pressure, not physical height. So lavt is exactly the natural word to use.