Learn Hardcore Swedish: Jag har en stor hund.

Swedish nouns are divided into two grammatical genders: en (common) and ett (neuter). Since hund (dog) is a common gender noun, the correct indefinite article is en.

Why is stor used here instead of something like stort or stora?

In Swedish, adjectives must agree with the gender and number of the noun. Because hund is a singular common gender noun, the adjective is used in its singular common form stor instead of the neuter form stort or the plural/definite form stora.

Does the adjective always come before the noun in Swedish?

Usually, the attributive adjective (an adjective modifying the noun directly) comes before the noun in Swedish, just like in English. So we say en stor hund (a big dog) rather than en hund stor. There are special cases (like some set expressions or certain formal/literary phrases) where the adjective can come after, but they’re less common.

Can I say Jag har stora hunden here?

No, because stora and the suffix -en imply a definite form. That would mean the big dog. To say a big dog, you need the indefinite form en stor hund.

Is there anything tricky about pronouncing har or hund?

In Swedish, har is pronounced with a softer 'h' sound and a long 'a'. Hund can sometimes drop the 'd' sound in everyday speech, sounding like hun. But both are acceptable—just remember that the 'u' in hund is pronounced a bit more forward in the mouth than in English.