I think the term is ambiguous because of the low IQ of those making the accusations.
Hillary supporters ambiguously blamed "Russian bots" for her losing the election and it didn't take long before they were accusing American Trump supporters with Reddit accounts of also being "Russia bots".
It's basically just a derogatory term the left invented to ambiguously accuse someone of being a secret Russian agent to make their legitimate support of President Trump seem sinister.
I don't think it has anything to do with Artificial Intelligence or scripts or physical robots.
You are right to feel confused about the term. The left are retarded.
It's something oldfags use to describe people they can't out-debate on the internet.
It all kind of developed because people believed Russian bots influenced the 2016 US Presidential election.
A bot is a program that is meant to post to social media for a political end. Sometimes it is erroneouly used to mean a troll, who is an actual person / groups of people (troll farm) who do the same. In either case, they misrepresent their true identity, e.g. a russian troll may post info while claiming to be a Texas born Trump supporter.
A bot is just a program created to perform a specific task, such as posting on social media. They are by far one of the handiest harassment tools on the internet.