acest student = studentul acesta
Acest student scrie o carte = This student is writing a book.
Studentul acesta scrie o carte = This student is writing a book.
(I used both,the meaning of the sentence is the same.The difference is that one uses the definite article.)
* Search for the usage of definite articles in Romanian!
copil - copilul : child - the child
om - omul : man - the man
carte - cartea : book - the book
vampir - vampirul : vampire - the vampire