The "nobody" user is a special user that generally possesses the minimum amount of permissions/access to complete a particular task.
From a security standpoint, this would prove beneficial as it wouldn't have access to tamper with files you wouldn't want it to access. This, in turn, limits access to site content files that are viewed publicly. As a result, select services such as Apache make use of this user. Processes spawned by Apache are under the "nobody" user, and the "httpd" processes owned by the "nobody" user would typically represent an active client connection:
[root@server ~]$ ps -u nobody
PID TTY TIME CMD
26057 ? 00:00:00 httpd
26058 ? 00:00:00 httpd
26059 ? 00:00:00 httpd
26060 ? 00:00:00 httpd
26061 ? 00:00:00 httpd
26441 ? 00:00:00 httpd
27931 ? 00:00:00 httpd
If you're experiencing a high count of these processes to the extent it began impacting performance, then you may want to look into reducing the MaxRequestWorkers value.
For more information on MaxRequestWorkers and instructions on tuning it, you may review the below article:
https://support.cpanel.net/hc/en-us/articles/360047992273