Maybe. Did you follow the instructions at JSR223 Scripting | openHAB, in particular installing the Experimental Next Gen Rules Engine (available under the Misc tab in PaperUI. Once you’ve done that I recommend following the instructions at Helper Libraries for openHAB Scripted Automation — openHAB Helper Libraries documentation or even better at [beta testers wanted!] Jython addon w/ helper libraries (requires OH 2.5.x).
This is required to set up Scripted Automation so you can run Rules in Python. As you can see with the last link, the steps to install it are getting easier and soon it will just require installing the add-on through PaperUI and in OH 3 it will just come installed by default.
openHAB has versions. You have the release versions (e.g. 2.5.1), testing or milestone releases (e.g. 2.5 M6 or milestone 6), and snapshots (e.g. 3.0-SNAPSHOT). That sentence means you need to run a version of OH, or at least a version of the MQTT binding that as released after the 2.5 M1 release which happened in February of last year IIRC.
Absolutely if you are using MQTT Eventbus by rkoshak · Pull Request #257 · openhab-scripters/openhab-helper-libraries · GitHub. It’s all in the docscrings (i.e. the comments between """ at the top of the file and in the Rule). In this case it says:
Called when a member of the Group defined by eb_out_gr in configuration.py
receives a command or an update. When the Rule triggers it publishes the
state or command to the MQTT topic
[eb_name]/out/[item name]/[state|command] where:
- eb_name: defined in configurations, the name of this OH instance
- item name: the name of the Item that triggerd the Rule
- state: when the Rule was triggered by an update
- command: when the Rule was triggered by a command.
When you first installed the Scripted Automation and the helper libraries per the instructions in the links above, one of the steps was to create this configuration.py file.
You missed the steps to install Python and the helper libraries.