Do you mean job queues (batch queues), print queues or print files? You can have as many print queues as you like, but there is a practical limit on job queues. On the AS/400 there is a maximum number of members you can have in a single file, and since the print files are stored in members, you can only have 32K of 'em.
You asked how many you're using. If you're talking about job queues and you're running an older version of OneWorld (i.e. XE or ERP8.0), you can look in the jde.ini on the server to find the number and names of the queues. If you're using a newer version (i.e. 8.9 to 8.12), there is an application in the System Administration area that has the queue maintenance application in it.
Could you please provide more information. Do you mean print or batch? Do you mean files or queues? What is your environment, platform, etc.