When your Viper scan is complete, you’ll see an overall plagiarism percentage (%) for the document. This percentage tells you how much content Viper found in your work which matches other sources online. The lower the percentage, the less that the work's content has been found to match with existing online sources.
Remember that not every bit of text flagged by the scan is a cause for concern. For example, some common phrases often show up as matching content simply due to how frequently they appear in a wide range of sources. Likewise, direct quotations will show as a match – this is perfectly fine as long as a suitable reference, showing where the quote has been cited from, can be found in the work! A correctly-formatted reference list will often show matched content, too, but this only shows that other online sources have used the same references as you: this is nothing to worry about!
You should look out for highlighted text in your document that isn’t correctly referenced, or is perhaps too similar to the original source. After making any necessary changes, you can re-scan your work to see if the plagiarism percentage has decreased. As a general rule, the lower the plagiarism percentage, the better - however, bear in mind that very few documents will ever score 0%.