In a personal computer application, to import is to open a file that is in a format different from the format the application creates on its own. Assuming the application knows how to import (reformat) the file, it does so and then opens it for the user to work on. Adobe Photoshop and other programs use this term. Other applications such as Word import files from another application such as WordPerfect simply as part of "opening" them.
After working with the opened file, an application user can usually simply "Save" or "Close" the file, leaving it in the current format, or can export it to another format. Some applications such as Word let you export a file by selecting the "Save as" function and specifying the desired format in the name suffix.