Worship LIVE! can attempt to import anything stored in a text file. Text files usually have extensions like ".txt", ".csv", ".tab", ".mus", ".crd", ".dat", or ".asc". If you are exporting songs from another program so the program can import them, carefully review the import dialog before you begin, to get a feel for the best way to export your songs.
The description of importing refers to "items" and "fields". An item would be any given property of a song, such as title, tempo, key, or lyrics. A field is a portion of the imported file that contains either the name of the item, such as "Title", or the item itself, such as "Holy Holy Holy".