Swedish for hello.
“Hejsan!” is probably the closest word that the Swedes have to “Hello!”, and is pronounced “HEY-san!”. There are other common variations, too. The abbreviated form, “Hej!”, is more like “Hey!” or “Hi!”. “God dag!” is more formal, meaning “Good day!”. Alternatively, you might hear “Hallå!”, which is generally used when answering the phone.
There’s also “Tja!” (pronounced “Sha!”), which is apparently “very informal”, but I have no idea what that actually means. The Swedish equivalent of “Bout ye?”, perhaps? 
Hallå is hello.
Hejsan is actually a colloquial form of hej. Most -san are colloquial versions — compare mor, morsan, far, farsan, bror, brorsan, etc.
Hej, in turn, isn’t really hey. It’s more neutral than that. You could say “hej” to somebody terminally ill without giving a hint of “how are you”. Maybe hi fits.
Tja, OTOH, is closer to “hey” or “eii!” Though it could be noted that tja has other definitions, like “well” in “Well, it *is* a long journey” which could be “Tja, det *är* en lång resa.”
HTH