Hi Maryam LAQLII,
From your question its very clear that you have DateAndTime attribute. When you importing data, each column represents each attribute of your entity.
So when your are importing some data, the column has to be date formatted while importing
For parsing: Use parse with. But it should take same type and parse.
For more information look into the documentation provided by mendix. You also parsing info in it.
https://docs.mendix.com/appstore/modules/excel-importer/#parse-with
Hope you find it helpful.