Appium/Selenium automation conventions in detail

Can anyone help me to explain the following convention/feedback in detail related to Appium/Selenium coding standard:

"You have good code structure in terms of package/class hierarchy and you use proper naming conventions at class and function level, however, there are a few feedbacks for further improvements:

• To use parametrization as all data is hardcoded
• To format the code
• To have abstraction at test case level as all element calls are made directly
• To implement asserts
• To avoid the usage of absolute xpaths to find web elements
• To execute test cases as API is not getting installed
• To make the code executable as there are library errors"

I am looking for answers related to how I can improve my test automation framework with reference to above. Some I know but want to see if my approach is relevant. This will also help a newbie in test automation.