Zipped files are compressed collections of files that make movement and downloading much easier than using folders. Compressions saves space and allows you to add password protection or encryption to files. The option of splitting a large file into multiple smaller files is available, and when this is done, zip part files are created. These files are like pieces of a puzzle; they're useless unless you hold the complete original. You can fix this easily.
Check the source where you downloaded the zip file from. Find out how many parts the zip file has. With zip files, you can only know the number of parts if the creator of the zip provides them.
Download all the parts into one location file directory on your computer. So if you had movie.zip, movie.zip1, movie.zip2 and movie.zip3 files they should all be in the same folder or location.
Right-click on any of the zip files that are a part of the collection and click on the "Extract here" or "Extract to folder" option in the pop-up menu. Your zip application will load up and begin decompressing all the files. A progression bar will appear on the screen and once it is fully loaded, it will fade away. A folder will appear with the uncompressed files ready to be accessed.