Learn Swedish: Han var så yr att han svimmade bakom bussen. - He was so dizzy that he fainted behind the bus.

It works exactly like "so ... that" in English! You place the adjective or adverb directly after så, followed by att (that) and then the rest of the clause. In this sentence, så yr att translates perfectly to "so dizzy that".

If the subject was plural (e.g., "They were so dizzy"), would the word yr change?

Yes. Even inside this så ... att structure, the adjective must still agree with the subject it describes. If the subject were plural, you would add an -a to the adjective: De var så yra att... (They were so dizzy that...).

What is the word order rule for the clause starting with att?

The word att introduces a subordinate clause (a dependent clause). This means the subject (han) comes first, followed by the verb (svimmade). As a quick refresher: if you needed to use a sentence adverb like inte (not), it would go before the verb in this type of clause: ...att han inte svimmade (...that he didn't faint).

Is yr the only way to say "dizzy" in Swedish?