You need just one word of Swedish
The Swedish word “tack” simply means “thanks”. But it is generally used to mean almost anything, while signifying that whatever you mean, you mean it to be polite. The particular meanings in actual situations are conveyed by gestures, intonation (a queryingly intonated “tack?”, uttered by a shop attendant, means “how can I help you?”) or by augmenting the “tack” with extra sounds or small words (aah, joo, njaa, etc.).
Asking in a roundabout way
This overuse of “tack” is partly due to the fact that Swedish doesn’t have a word for “please” in the asking or begging sense, like in “Please pass the salt” or “Please lend me 10 €”. Most languages have a specific word for this "politely-asking"-function, like the English word "please" or the German "bitte", but Swedish lacks such a word. So Swedes have to circumvent this peculiar linguistic deficiency by using various roundabout queries, e.g. “Could you be so kind as to pass me the salt?”, “May I ask you to lend me 10 €?”
There is a “please” in Swedish in a different sense, the sense you apply when you are politely offering a person something, “Please, here is your beer!”, “Please help yourself to some cookies!”. This latter meaning is conveyed in Swedish by the word “varsågod”, approximately pronounced “vaah-shaw-good”.
No please, thank you!
To fill the void of the missing “please” in Swedish, the word “tack” (thanks), an expression of politeness, has expanded to cover the asking sense of the polite English “please”. So if you order something (a large beer, for example), and want to be polite, then you have to say “A large beer, thank you” (“En stor öl, tack”). This expansion in meaning has in turn lead to “tack” being used to cover a multitude of linguistic needs in many situations. When you are for instance entering a shop, the shop attendant’s “Tack?” works as “What are you interested in buying?”, and when leaving the shop your “Tack!” works as “goodbye”.
On a shopping spree, sounding like a machine gun
So at least during your first hours in Sweden you will get by splendidly with just one word of Swedish -- “tack”. Here is an example of the monosyllabic conversation that you and some shop attendant may have on your first shopping spree in Stockholm. Note that “tack” is frequently multiplied, making people sound like machine guns –- tack-tack-tack-tack -- :
You (entering shop): -- Tack ...
Shop attendant: -- Tack?
You (pointing to an item): -- Tack!
Shop attendant (fetching item): -- Tack, tack!
You (nodding in approval): -- Tack, tack-tack!
Shop attendant (taking your money): -- Tack, tack-tack-tack! Tack!
You (leaving shop): -- Tack!
Shop attendant: -- Tack-tack!
NOTE:It should be perfectly clear to anyone that the above shopping dialogue is in part a cheerfully twisted satire. But this doesn't make it any less true that the Swedish frequency of "tack", "tack-tack" and "tack-tack-tack" is surprisingly high and that its use in surprising situations is certain to surprise a foreigner.