I think there are a couple of major things: 
1 - We believe that our Church is the restored Church that Christ himself established when he lived on the earth. 
2 - We believe we have modern revelation from Heavenly Father to His restored Church through modern-day prophets and apostles 
3 - We believe that God's priesthood - his authority to act in His name - has been restored to the earth 
4 - We believe that we as individuals can receive inspiration and revelation for ourselves through the Holy Ghost. The Gift of the Holy Ghost can be given to people again on the earth because the priesthood has been restored. 
5 - In summary, we believe that God has restored His church and full truth to the earth. 
 
 
Here is a summary of our major beliefs. They are called the 13 Articles of Faith: Link 
 
Also - here is another website with more in-depth explanation of some of our basic beliefs: Link