Learn Swedish: Snälla, öppna dörren!

The imperative (command) form is always just the stem of the verb. For a very large group of Swedish verbs, the stem naturally ends in -a. Because of this, the imperative öppna and the infinitive att öppna (to open) are exactly the same word.

I learned that "please" is tack. Why is snälla used here instead?

You use tack when you are politely asking for an item, like in a cafe ("En kaffe, tack"). But when you are making a direct request or begging someone to do an action, like opening a door, you use snälla. It actually comes from the Swedish adjective for "kind" or "nice".

Wait, where is the word for "the" in öppna dörren?

In Swedish, "the" isn't a separate word that goes before the noun. Instead, it gets attached to the end of the word. The basic noun is en dörr (a door). When you add -en to the end, it becomes dörren (the door).

Why is there no word for "you" in this sentence?

Just like in English, when you use the imperative mood to tell someone to do something, the "you" is already understood. You don't need to include the Swedish word for you (du); you can just say öppna dörren!