Hi,
"Over two" means you are stitching over two squares on the fabric.
So, let's say you are stitching a pattern on 14-count Aida and going over one square, then that means you are going "over one".
If this is still confusing to you, go to a website called "scarletquince.com". At the top of the website you will see different categories, Tap on the "solutions" bar then on the "tips" bar which will bring up a menu to your left with different titles. Look under the STITCHING title to where it says "over 1 and 2" and tap on it. It will bring up a menu with different instructions but if you scroll up, you will see in RED print about diagram over 1 and over 2. Tap on ithe red print and you will show you an example diagram of "over one versus "over two".

I did not know that! Thank you for the question and the answer! I am not new to cross stitching but am back to it after many years! Thanks!

I did not know that! Thank you for the question and the answer! I am not new to cross stitching but am back to it after many years! Thanks!