Learn Hardcore German: Stell bitte den Roller vor dem Museum ab, dann gehen wir zum Eingang. - Please park the scooter in front of the museum, then we go to the entrance.

stellen → Stell! (common) / Stelle! (also correct, a bit more formal or emphatic)
So Stell bitte ... ab is a normal, natural way to tell one person to do something.

What does bitte do in this sentence—does it mean “please” or something else?

Here bitte means please and softens the command:

Stell den Roller ab. = more direct
Stell bitte den Roller ab. = more polite / friendly
German also uses bitte in other ways (e.g., You’re welcome, Here you go), but in an imperative it’s typically please.

Why is ab all the way at the end of the first clause?

Because abstellen is a separable verb: ab- + stellen. In main clauses, the conjugated verb part (stell) goes in position 2, and the separable prefix (ab) goes to the end of the clause:

Du stellst den Roller vor dem Museum ab.
Stell den Roller vor dem Museum ab.
In subordinate clauses, it stays together: ..., weil du den Roller vor dem Museum abstellst.

Is den Roller accusative? How can I tell?

Yes, den Roller is accusative. The verb (etwas) abstellen takes a direct object: you “park/place” something.
The masculine article changes from der (nominative) to den (accusative):

der Roller (subject form)
den Roller (object form)

Why is it vor dem Museum and not vor das Museum?

vor is a two-way preposition (Wechselpräposition): it takes

dative for location (where something is),
accusative for direction/movement toward a destination (where something is going).

Here you’re being told to park it in front of the museum (final location), so German conceptualizes it as location → dative:

vor dem Museum (dative: dem) = in front of the museum (park it there)

You’d use accusative more in “move it to in front of ...” type framing, e.g. Stell den Roller vor das Museum can be possible in some contexts, but vor dem Museum abstellen is the standard phrasing for “park in front of.”

What’s the difference between stellen and legen here? Why abstellen?

stellen = put something upright / standing (or generally “place/put” for objects that stand)
legen = lay something down / flat
abstellen = “park/put down and leave (for a while)”, often used for vehicles/objects you leave somewhere: Fahrrad, Roller, Auto (park), etc.

So den Roller abstellen naturally means “park the scooter (and leave it there).”

Does Roller mean a kick scooter or a motor scooter?

Roller can mean either, depending on context and region, but in general German Roller often refers to a motor scooter (like a Vespa-style vehicle).
If someone specifically means a kick scooter, they may say Tretroller or (in many places) E-Scooter for an electric rental-style scooter.

Why is there a comma before dann?

Because this sentence contains two main clauses joined in one sentence:
1) Stell ... ab
2) dann gehen wir ...

A comma is commonly used to separate such clauses, especially when the second begins with an adverb like dann and it’s clearly a new clause. It improves readability and is very typical in written German.

Why is the word order dann gehen wir and not dann wir gehen?

In a German main clause, the finite verb must be in position 2 (V2 rule). If dann is in position 1, the verb must come next:

Dann gehen wir zum Eingang. ✅
Not: Dann wir gehen ... ❌

What does zum mean, and why not zu dem?

zum is the contraction of zu dem.

zu takes dative
der Eingang is masculine → dative is dem
So: zu dem Eingang → zum Eingang.
Both are correct, but zum is the normal everyday form.

Why is it zum Eingang and not in den Eingang?

zum Eingang means to the entrance (toward it, destination). That’s what you do when you’re outside and walking there.
in den Eingang would mean into the entrance/entryway (crossing into the interior space), which is a different idea and sounds odd unless you mean going inside the entry area.

Could you also say zum Museumseingang?

Yes. German often forms compound nouns:

zum Eingang = to the entrance (context tells which one)
zum Museumseingang = to the museum entrance (more specific)

Both are natural; the compound is used when you want to be explicit.

Who is being addressed, and who is included in wir?

Stell ... ab is an imperative for du, so it’s addressed to one person (the listener).
wir means we = the speaker plus at least one other person (often the listener too). In context, it usually means: “You park it, then we (you and I) go to the entrance.”

Can Stell be for ihr or Sie as well?

Not as written. Imperatives differ by pronoun:

du: Stell (bitte) ... ab!
ihr: Stellt (bitte) ... ab!
Sie (formal): Stellen Sie (bitte) ... ab!

So Stell signals you’re speaking informally to one person.

Is the time sequence (“first…, then…”) expressed by dann alone?

Yes. dann clearly signals the next step: “then/after that.”
You can also use alternatives depending on nuance:

danach = after that (often more “afterwards”)
anschließend = afterwards/subsequently (more formal)
But dann is the most straightforward for spoken instructions.

If I wanted to make the first part more polite, what could I change?

Common options:

Add mal (casual softener): Stell bitte mal den Roller ... ab.
Use a question-like suggestion: Kannst du den Roller ... abstellen?
Use formal Sie: Stellen Sie bitte den Roller ... ab.
The original is already polite because of bitte.