Since you had trouble coming up with an edit description, here are some key words and phrases I use when editing. Some I picked up in my English/writing classes during my school days. Others are just obvious or something I can up with.
- grammar: This covers things like word order, verb tenses, prepositions ("of", "to", "on"), articles ("a", "the", "some"), pronouns, run on and incomplete sentences, plural vs. singular, etc.
- mechanics: This covers spelling, punctuation, capitalization, etc.
- word choice: This is when the word chosen doesn't quite mean exactly what they intended to communicate.
- awkward phrasing: This is for when I can't really pin down an exacta technical reason it's wrong, but I know that it definitely doesn't soundread very smoothly. (This sometimes corresponds to when it doesn't read like native speech.)
- formatting: I only use this when I'm doing Markdown stuff. Turning something into a code block or a block quote, fixing some list indentation, bold, italics, turning lines into headers, etc.
If you can, always be more specific. But if the changes you made are too wide ranging to stuff all the details into that description, sticking "fixed" in front of the above phrases can help summarize in a lot of cases. Try not to let these summaries stand completely alone whenever possible.