You can catch Friday prayer up with one rak`ah. If you catch up with the second rak`ah prayed with the imam, then you can pray it as Jumu`ah. If you catch up with a person who is making up the rak`ah that he missed and pray with him, then you should pray it as Zhuhr and not as Jumu`ah.

It is haram to miss Jumu’ah prayer. If you do not attend Jumu’ah without a valid reason, you will be committing a major sin. Whoever does not attend three Jumu`ahs (in a row) out of negligence has a seal placed over his heart.