The five prisoners our government so stupidly released for one pathetic traitor are now fighting and killing for ISIS-BAD DEAL! Courtmarshal
Who are the five prisoners? Whom did Trump call a "traitor"?
Judging by both the context and the time of the tweet (1 Nov 2014):
The "traitor" was about Bowe Bergdahl
On December 14, 2015, the U.S. Army announced that Bergdahl would be tried by general court-martial on charges of desertion and misbehavior before the enemy
Bergdahl wrote e-mails to his parents in which he reported having become disillusioned with the war effort and bothered by the treatment of Afghans by American soldiers. He said in his e-mail he was ashamed to be American
Some soldiers who served with Bergdahl have called him a deserter
While technically, "traitor" doesn't seem legally applicable given the known facts, the following may have been the reason (as well as identities of 5 prisoners, see below):
According to soldiers involved in the operations to find Bergdahl, at least six soldiers were killed in the search; this includes six soldiers in the same battalion as Bergdahl.
Five prisoners (aka "Taliban Five") were exchanged for Bergdahl by Obama administration:
Bergdahl was released on May 31, 2014, as part of a prisoner exchange for five Taliban members who were being held at the detention center at Guantanamo Bay.
Don't let "five members" wording lull you into thinking "Big deal!". The five were:
Abdul Haq Wasiq was deputy chief of the Taliban regime's intelligence service. Wasiq had direct access to Taliban and Hezb-e-Islarni Gulbuddin leaders
Norullah Noori served as the governor of Balkh and Laghman provinces in the Taliban regime. He was a senior Taliban military commander in Mazar-e-Sharif. Noori is "wanted by the United Nations for possible war crimes including the murder of thousands of Shiite Muslims" along with Fazl.
Mohammad Fazl served as Chief of Staff of the Taliban Army. He was associated with terrorist groups opposing US and Coalition forces. According to documents from the Joint Task Force Guantánamo, Fazl is "wanted by the UN for possible War crimes including the murder of thousands of Shiites"
Khairullah Khairkhwa was the interior minister under the Taliban. He helped found the Taliban in 1994. He was directly associated with Osama Bin Laden and Taliban Supreme Commander Mullah Muhammad Omar. Likely involved with militant training, he was also "a narcotics trafficker and probably used his position and influences to become one of the major opium drug lords in Western Afghanistan", and probably used profits from drugs to promote Taliban interests
Mohammad Nabi Omari was the Taliban's chief of communications. Nabi had "operational ties to Anti-Coalition Militia (ACM) groups including al-Qaida, the Taliban, the Haqqani Network, and the Hezb-e-Islami Gulbuddin".