Hello Sofiaisnot,
It sounds like you have an old iPad that is locked.
Knowing how exactly the iPad is locked, can be helpful. Here are some resources might cover this:
Is it the case that you don't know the passcode to the iPad and it shows it's disabled? If so, review this article If you forgot the passcode on your iPhone, or your iPhone is disabled or see Apple Support's YouTube video on this How to restore your iPhone if you forgot your passcode - Apple Support
Are you seeing Activation Lock requesting your Apple ID and password as seen here Activation Lock for iPhone, iPad, and iPod touch. If so, check out the following:
When it comes to trading in your iPad, if you are looking to do that through Apple, see what recycling or trade in programs you have available in your location here Apple Recycling Programs. If you choose to trade in your device, you will need to turn Activation Lock off.
Hope this information helps.
Have a good day.