Retrieve data from Entity: Account ( Name , Descripting)

Dear all . 

I am student . I would like you help advise me . 

 I want get data from entity:Account with Attribute ( Name , Description) Key is : accountid 

And I want to update this data to Entity:Task (Description = Name + '/'+ Description ) Referent key with Account Key is : regardingobjectid

In this I what i want update data on task when i try edit on account . 

thank you  all .