I know my apple ID but don't know my iCloud id or password, is it the same? I am preparing to buy a new iPhone but the salesmen said I need the iCloud address and password.  I have no idea what that is.  Is it the same as my apple id?
An Apple ID is used to log in to iCloud services if you choose to use them. You can have multiple Apple IDs, but one is signified as the ’primary’ account and used for iCloud. When one asks for an ‘iCloud ID’, they refer to the Apple ID used for iCloud.

In this case, it seems a device has activation lock. You'll need the owner's Apple ID used for iCloud to unlock the device before you can use it.

Never give your Apple ID password to anyone.