Hi
You can find explanation for all these actions on help.sap.com
Please do research yourself first before posting questions on SCN. You can use google search to find relevant posts or information.
Use google with following keyword for example:
help.sap.com preliminary import requested
https://help.sap.com/saphelp_sm71_sp12/helpdata/en/d6/e6bcc740964311987d440ab83e6684/content.htm
Best regards
Tom
