No, java jar files are basically a kind of archive liek zip. But they can be executed.
So download the zip file from here first:
https://cdn.mmoui.com/minion/v3/Minion3.0.5-java.zip
Extract all contents (the .jar file and the folder libs) to a directory c:\minion.
Create the folder if it doesn't exists first!
Then open teh command line with admin rights, e.g. press Win key, type "cmd" and you'll see the found command prompt entry. Right click it and say "Run as administrator".
In the command prompt change the directory to the drive and folder where you have extracted the minion jar to with the commands: <return> means you need to press the return key.
c: <return>
cd Minion <return>
Then execute the jar file with the java command:
java -jar Minion-jfx.jar <return>
Normally Minion should run then, using your installed Java JRE (Java runtime environment) version (the command "java" before "-jar Minion-jfx.jar" is executing the java.exe file from your System Environment variables -> They know where the java vesion is installed and uses it) which was mentioned above. Current version is
8 Update 221
https://www.java.com/de/download/win10.jsp