To take the bull by the horns means to deal with a difficult situation in a brave and firm way.
Don't suffer in silence while your flatmate takes up all the space. Take the bull by the horns; tell him to move his things out of your way or move out!
Bob was treated very badly by his boss. When he left the company he decided to take the bull by the horns - and sued it for thousands of dollars.
When you say someone is like a bull in a china shop you mean that they are too clumsy to deal with a delicate situation.
I will be the one to go and ask our neighbour to stop playing his music so loud. You are like a bull in a china shop and are likely to start a serious argument with him.
At the San Fermín running of the bulls festival in Pamplona, bulls are allowed to run wild around the streets sometimes knocking people out of the way. A similar event is held in towns and villages across Spain, Portugal, in some cities in Mexico, and the south of France.