Learn Swedish: Frisyren blir nog helt perfekt. - The hairstyle will probably turn out absolutely perfect.

The verb bli (to become) is often used to express how something will "turn out" or result after a process. Using blir here instead of a basic future tense emphasizes the final result of the haircut being finished.

I learned that nog means "enough." Why is it translated as "probably" here?

You are right that nog means "enough" in phrases like stor nog (big enough). However, when placed in the middle of a sentence like this, it acts as a "modal particle"—a small word that shows the speaker's attitude—meaning "probably," "likely," or "I reckon."

Why is there a -t on the end of helt?

In this sentence, helt is acting as an adverb modifying the adjective perfekt, meaning "completely" or "absolutely." In Swedish, you create adverbs from adjectives by adding a -t, which looks identical to the ett-word adjective form.

Since perfekt comes after the verb, does it still need to agree with frisyren?

Yes! Adjectives that come after verbs like är and blir (called predicative adjectives) still have to match the noun they describe. Because frisyren is an en-word, perfekt takes the base en-word form with no extra ending.