How can I find out what’s in “other” on my iPad storage?

Other storage cannot be “explored”. Files included in this category include cached files, such as your Web Browser(s) - and data/files for which there is no matching App.

If, when looking at your data storage usage, you see that the “other” category is consuming an disproportionate amount of space on your iPad, this support page may be helpful to you:

Clear Other storage on your iPhone or iPad - Apple Support

I hope this information and guidance proves to be helpful in resolving an issue - should you have one.