the three powers Congress had are
1) making laws
2) amending the Constitution
3) the power of the purse
making laws is important because laws don't just appear and we'll go through a lengthy process to become official laws are important to maintain the social class and economic balance of power
amending the Constitution is important because laws placed in the construction back in the day may not be considered humane or " right " and should be changed to fit the moral of today's society
the power of purse is important for all financial power such as taxes , controlling currency exchange, ect