what happens when I erase my device

First, understand that you can only remotely erase a device, using the Find Me App, if the target device has an active WiFi or Cellular network connection.

If the target device isn’t powered-on - and/or the device doesn’t have an active network connection - the erase command will not be forwarded to, or received by, the device. Instead, the instruction remains dormant on Apple’s servers until such time as:

a) the target device is powered on, has an active WiFi or Cellular connection - and connects to Apple’s servers

b) the remote erase command is cancelled by the owner

Assuming that the remote erase command is received by the device, the entire device is automatically reset/erased. The cryptographic keys that are required to access the device’s encrypted file-system are destroyed - making all locally stored data permanently unrecoverable.

One erased, the Activation Lock remains active. The iPad cannot be setup, or used again, by anyone other than the owner who last successfully activated the device with their AppleID credentials.

All of your documents on your iPad are deleted, if any documents are on iCloud Drive, they will not be deleted. Any apps that are synced with iCloud Drive will keep their data, and all of your apps will be deleted. Your iPad name will be reset, and you will have to manually set your language, WIFI, and set up your iPad.