再来週 (saraishū) means “week after next”

More examples

再来週に家族と旅行へ行きます。sa rai shū ni ka zoku to ryo kō e i ki ma su

I will go on a trip with my family the week after next.

Points to the week that arrives after the upcoming week, rather than the upcoming week itself.

来週のさらに次に当たる週。rai shū no sa ra ni tsugi ni a ta ru shū

再 (sai, "again") + 来 (rai, "come") + 週 (shū, "week") forms 再来週 (saraishū), the week that comes again after the next week.

In everyday scheduling, 再来週中 (saraishūchū) means at some point during the week after next, while 再来週の月曜日 (saraishū no getsuyōbi) names a specific day.