Learn Hardcore Swedish: Jag låser alltid dörren på kvällen.

Swedish main clauses follow the V2 rule: the finite verb must be in second position. In a neutral sentence starting with the subject, you get Subject–Verb–(sentence adverbs like alltid/inte)–Object–Time/Place.

Correct: Jag låser alltid dörren på kvällen.
Wrong: Jag alltid låser dörren...

If you move something else to the front, the verb still stays second and the sentence adverb stays after the verb:

På kvällen låser jag alltid dörren.
Då låser jag alltid dörren.

Can I start the sentence with the time phrase?

Yes. Fronting a time expression is very common in Swedish. Keep the finite verb in second position and alltid after it:

På kvällen låser jag alltid dörren.

Could I say Jag låser dörren alltid på kvällen?

It’s possible but marked. Neutral Swedish places sentence adverbs like alltid before a full noun object:

Neutral: Jag låser alltid dörren på kvällen.
Marked/emphatic: Jag låser dörren alltid på kvällen.

If the object is a pronoun, it typically comes before the adverb:

Jag låser den alltid på kvällen.

Why is it dörren (definite) and not just dörr or en dörr?

Swedish marks definiteness with a suffix. Here, you mean “the door” (the one to your home/room), so you use the definite form dörren. Saying en dörr would mean “a door” (any door), which sounds odd in this context.

Do I need to say min dörr (“my door”)?

Usually no. Swedish often uses the definite form without a possessive when ownership is obvious from the subject:

Jag låser dörren. = I lock my door (implied). Use min dörr only if you need to contrast or specify whose door:
Jag låser min dörr, inte grannens.

Why is it på kvällen and not i kvällen?

For general times of day, Swedish uses på + definite singular:

på morgonen, på eftermiddagen, på kvällen, på natten

The phrase i kväll is a special case meaning “tonight/this evening.” You cannot say i kvällen for “in the evening (in general).”

What’s the difference between på kvällen, på kvällarna, and om kvällarna?

på kvällen can mean either “in the evening (of a given day)” or “in the evening” as a general habit.
på kvällarna and om kvällarna both clearly mean “in the evenings” (habitual, plural). Examples:
Habitual, neutral: Jag tränar på kvällen.
Habitual, explicit plural: Jag tränar på kvällarna / om kvällarna.
Specific day: Vi hörs på kvällen (efter jobbet).

What tense is låser? Do I need something like “usually”?

låser is present tense and is used for habits and general truths, just like English simple present. If you want “usually,” use brukar:

Jag låser alltid dörren på kvällen. (always)
Jag brukar låsa dörren på kvällen. (usually)

Is låsa the right verb here? How is it different from stänga?

låsa = to lock (with a lock/key/bolt).
stänga = to close/shut. You typically do both: first stänga dörren (close the door), then låsa dörren (lock it).

How do I conjugate låsa?

It’s a regular Group 2 verb (like läsa):

Infinitive: att låsa
Present: låser
Past: låste
Supine (with har): har låst
Imperative: Lås! Also useful: “The door is locked” = Dörren är låst.

Any tips on pronunciation for the words in the sentence?

Jag: often pronounced [jaː]; the final g is often very soft or silent.
låser: long å [oː]; roughly “LOH-ser.”
alltid: double l is long; the final d is often weak or dropped in casual speech (“allti”).
dörren: short ö (like French “peur”); double rr is a long r sound.
på: long å [oː].
kvällen: kv as in “kv”; ä like “bed”; double ll long.

Vowel keys: å ≈ “aw”/“o” in “law” (but rounded), ä ≈ “e” in “bed,” ö ≈ French “eu.”

Where does negation go, and how does it interact with alltid?

Both inte and alltid are sentence adverbs and go after the finite verb. Their order changes meaning:

Jag låser inte alltid dörren. = I don’t always lock the door. Avoid: Jag låser alltid inte dörren. (unnatural) With a pronoun object, the pronoun comes before the adverb:
Jag låser den inte på kvällen.
Jag låser den alltid på kvällen.

Can I talk about the future with this structure?

Yes. If you add a future auxiliary, it becomes the finite verb, so alltid still comes right after it:

Jag ska alltid låsa dörren på kvällen.
Jag kommer alltid att låsa dörren på kvällen.

Is there anything special about capitalization of jag?

Yes. Unlike English “I,” Swedish jag is not capitalized unless it starts the sentence. In our example it is capitalized only because it’s the first word.