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English Grammar Terms (again)

Hello again!

I have a couple more terms that I am just not able to remember or find anywhere (since I have no idea where to start when trying to look it up).

The word "information" is seemingly singular and plural at the same time. The word "informations" does not exist. What are words like this called??

And in the sentence: "Yes, I've been to the bank yesterday."
That is obviously wrong and should be said: "Yes, I was at the bank yesterday" or "I went to the bank yesterday"

Which grammar terms tell what is wrong with the incorrect sentence, and which grammar terms explain what is right about the correct sentences?

Thank you very much!
"Lilith"

PS- Also, is there any really good English grammar website that you could recommend? I have found a lot with terminology, but the explainations are not worth anything.