Learn Dutch: Jij komt juist op tijd. - You arrive right on time.

Jij is the stressed form of the pronoun "you". You use it when you want to put special emphasis on the person. In English, you would show this with your tone of voice: "You arrive right on time."

Why does it use komt (to come) instead of a word for "arrive"?

Literally, this says "You come right on time." In Dutch, using komen is the most common and natural way to express arriving somewhere. You can use the verb aankomen (to arrive), but komen is used much more often in everyday speech.

I learned that juist means "correct". How is it used here?

You're right that juist often means "correct". However, it can also be used as an adverb meaning "exactly", "just", or "right". In this sentence, juist op tijd translates to "right on time" or "exactly on time".

Does op tijd mean "on time" or "in time"?

It actually means both! Dutch uses op tijd whether you are arriving precisely at the scheduled moment ("on time") or arriving before it's too late ("in time").