Well, considering the price point at which the Samsung Galaxy J3 has been launched, it would have been strange if the feature was not available on it. Yes, the Galaxy J3 has the USB OTG functionality. You can connect the external drives that you may have to your device and view the files stored on them on your smartphone. Please check for the file system compatibility between the smartphone and the external drive connected. If there is a compatibility issue, you may need to format the drive to the supported format. Ensure you have backed up the data on the drive before proceeding with the formatting.
Also please note that the USB OTG cable is not available as part of the sales package. You will need to buy it as a separate accessory.
Live....and Let Live!