This meeting was about Trump Jr. seeking to gain secret negative information on Hillary (what Trump Jr. said he wanted from the meeting)--in exchange for Trump Sr. seeking to drop US sanctions on 18 Russians connected to Putin. The sanctions were imposed under the US Magnitsky Act (which was a topic for the meeting). And if this happened, then Russia would also drop its sanction on US adoptions of Russian children (also a purpose of the meeting). The mere discussion of these possible tradeoffs is a felony violation of Federal Law if the representatives of the US are private citizens and not authorized government officials. This was one reason Trump Jr. tried so hard to cover this up and was constantly having to change is story.