>>I’m an old guy and not familiar with what you are trying to tell me
No problem. Lots of old guys, me included, and possibly older girls, here -and younger ones.
>>I assume you have visited Settings/Passwords and looked at the entry for the particular site?
Open up Settings on your desktop. Scroll down to Passwords and open that; you will have to use Touch ID, FaceID or your iPad passcode to go further. You will (hopefully) find a list of all the web sites you visit. Scroll down to the site in question. Tap on the website name and the web site info will open up displaying your Username and Password for the site. Top right hand corner is edit. You can edit or delete either if one or other is incorrect. There is also a button to delete the site password.
Just a thought: Go back up to the list of sites. It is possible that your site is entered twice in the list of passwords. You can also swipe left on a web site and delete the whole entry.
>>Perhaps after you have deleted the existing entry, do an iPad soft reset
There is an extremely useful reset on both iPads and iPhones, the soft reset, which simply clears away left over items in the device memory. It does not reset the device to say Factory Level, that is done another way. Also it does not delete files, apps or folders; it simply does what perhaps can best be described by me as a tidy up.
The soft reset method depends on your iPad model. I have an old 'Air 2', with a home button. On this I press and hold the home button and press and hold the power button; keeping both pressed until the screen goes black and then the Apple icon reappears. Once the Apple icon appears, release the buttons.
You may need to type iPad Soft Reset into a search engine, together with your model of iPad to find the actual method for your iPad. Alternatively, ask here, and someone will be along with the correct method for your iPad model,
As mentioned above, the Soft Reset is really useful and is almost always the first thing to do if your device is not working as you expect. For example: an app freezes; an app doesn't open as you expect; the iPad just doesn't 'feel' right....
I hope that the above helps you.