Here are two related sentences
Daniel has some very interesting ideas.
He is a leading thinker in his field.
Combing these two sentences makes a much more elegant sentence:
Daniel, who is a leading thinker in his field, has some very interesting ideas.
The example sentence uses a relative pronoun to combine the two sentences through a relative clause. This combination exercise focuses on changing two simple sentence into complex sentences.

Comments
Joseph, a leading thinker in his field, has fine ideas.
How is this?
Whenever using a sentence, where commas are applied, we call it: “Non-defining clause”. In other words, it is easier, and clearer to understand it. Whilst the opposite is called:”Defining clause”. (without any commas).
Londrina Brasil.
I think it is very important point about the use o comman in english. is there something about in this site!!!