Answer:
Congress was allowed to handle all national and foreign relations, trades, as well as appointing officials to offices that dealt with foreign relations, the military, and the Native Americans relations.
It is important to note, however, that Congress was not allowed to raise any type of tax (or what is now known as the national tax), as the power was left to the states to decide on a per-state tax rate. The only way for Congress to raise money, therefore, was to ask the states for funding, or to borrow money from entities and even sell national lands to raise funds.
Of course, with such limiting powers which left all branches of the government without any abilities to run a functioning government, the Articles of Confederation was soon replaced with the Constitution of the United States, which is still in use until today.