I instal pakage BimorphNodes bus!!..
This is a standard warning to let you know that the package contains code which could have been expanded beyond basic Dynamo interactions and could include potentially harmful code. This is pretty much every major package out there. It does not mean that the package is harmful.
It’s on you as a computational designer to review each such package and decide if there is any exposure concerns. Review stuff like number of installations, profile of the author, and scope of interaction.
In the case of BiMorph nodes: there are many installations of the package; the author is very well known and interacts daily with the larger community as this is how he makes a living, using his real name, and is a pretty cool guy all around; the package makes many calls to the Revit API in order to make a more efficient code base that what Dynamo can do out of the box or to expose content which otherwise isn’t there.
All of this is to say that if I were you I’d go ahead and download the package and check out the code base it contains so you can take advantage of this (and others) great community resource with a great degree of certainty that you will be ok.
Conversely you might want to hold off if: the package has a handful of downloads and is new to package manager; authored by a shadowy screen name which didn’t have a history in the larger community; had descriptions which sound weird or too good to be true.