Max CPU is the max CPU value in a given 5 minute (Default) performance counter interval for the QlikView Server service.
QlikView Server produces a performance log which tracks some performance counters like CPU load, RAM allocated, etc. Default setting is every 5 minutes.
The Governance Dashboard reads in these performance logs and reports them. So if you see Max CPU of 55%, you would know that during the specific timeframe, the QlikView Server service was operating at 55% during one of the 5-minute intervals.
Note that this is not total CPU for a server. Just for QlikView Server service.