After JENKINS-60920 (I guess?), the header bar shows <bell icon> monitors 2 and the tooltip shows

bq . There are 2 active administrative monitors.

We should not be using the bare term "monitor" in the GUI. This word in English has various meanings (video displays, bureaucratic police, ...) but none of them would be intuitive in this context. In some spots in the GUI like /configure we do use the phrase "administrative monitor" which is more tolerable, though something like "alert" or "notification" would be more conventional. (I think the Java API introduced AdministrativeMonitor to describe how the implementations are written—by monitoring some condition and conditionally displaying the result to administrators—but this does not well capture the user's perspective.)

I would suggest just deleting the word from the toolbar. The bell icon suffices for people to understand that there are some alerts they can see by clicking on it.