As others have said in the comments, this means you have 395 issues in your code (kind of like lint warnings).
Detekt has a maxissues: property that determines whether or not to fail the build if your issues surpass the allowed number of maxissues. What I did was search the whole project for maxissues, which will take you to your detekt-config.yml or default-detekt-config.yml. There, you can change your maxissues to whatever you want.
In our old code base, we had 900 some issues, so I changed mine from maxissues:0 to masissues:1000. As we clean up the code, I hope to bring that number down.