Bicameralism separated the legislative branch of government into two bodies. One body to represent individual districts (the house of Representative) and one body to represent the state (Senate).
The purpose of creating this separation is to check the power of the legislative branch. The decisions made by the house of representatives is mostly related to the use of State' fund to pay for the programs/infrastructures on the local level.
The decisions made by the Senate on the other hand could affect the nation as a whole. Senates are involved in vetting potential judges for the supreme court, conducting an impeachment, negotiating trade agreements across states, etc.
