The Manifest.db is a SQLite database storing information about the iTunes backup. When opened with DB Browser for SQLite, switch to the Browse Data tab to preview the contents of the tables.
In the above photo, you can see the table’s contents on the left side. When you see BLOB as the content, you will likely want to export the data to view in another application. To see the content in SQLite, on the right side, change the Mode to Binary. This will show you the BLOB content, which in this case is an embedded binary plist. (Welcome to iOS and macOS! You will quickly get used to seeing embedded binary plists, double embedded plists, and so on. It is plist Inception!)
To export the binary plist, click on Export and save the file to a new location. Change the file extension to plist and open with your plist viewer of choice. (On macOS, you can view these natively or use Xcode. On Windows, try Paul Sanderson’s BPList Viewer.)
The exported plist will include file information and dates, depending on which binary plist you exported. The highlighted item “LastStatusChange” is actually a date value of Unix Epoch. If you see a number starting with 14 or 15, count on it being a Unix Epoch date.
In the above example, the Unix Epoch value “1527733038” has been converted to a human-readable date. EpochConverter.com is a great, free resource for converting date values and allows batch conversions of dates. Other popular conversion tools are Dcode, DateDecode, Unix Timestamp, and my personal favorite epochalypse.py.