And just to spell it out.

• Trump Jr.'s email literally says "This is obviously very high level and sensitive information but is part of Russia and its government's support for Mr. Trump - helped along by Aras and Emin." It literally says the Russian government is behind the information
• Trump Jr.'s email says that she's a "russian government attorney". Even if she isn't a government employee, the email itself presents her as one. So Trump Jr. was told he was going into a meeting with a government employee.
• Trump Jr. also forwards the entire email chain to Kushner and Manafort who now have also been told that this was a meeting with a "russian government attorney". Kushner has failed to disclose this content in his security clearances (all contact with foreign government officials need to be documented so the intelligence agencies can ensure the safety). So Kushner is either a) incompetent and can't keep track of all his contacts with foreign government officials or b) he is hiding his contact with foreign government officials.
• • These lapses should immediately revoke his security clearance until the connection is investigated. Lying on these forms is a felony.
• Trump Jr.'s statement said they talked about adoption policy and the Magnitsky act. ( The Russian adoption policy was enacted in retaliation to the sanctions in the Magnitsky act -
  https://en.wikipedia.org/wiki/Magnitsky_Act). Basically she's asking for political favors in exchange for the information. Essentially: "We'll give you opposition research if you give leeway on sanctions"
• • Jr. is downplaying an obvious deal in front of him.

For those following along, here's the email from the source himself spread over two tweets:
https://twitter.com/DonaldJTrumpJr/status/884789839522140166
https://twitter.com/DonaldJTrumpJr/status/884789418455953413