You can add as many Gmail email accounts as you need to in the app settings for the Gmail App. I currently have 3 in mine. If the device is set up with a Google Work profile the apps will be split in to a personal app and a work app. These apps will have different abilities based on the set up of the Google work profile. You can find additional information at the link below.
https://support.google.com/work/android/answer/6191949?hl=en&ref_topic=7069773