***** NOT A TEACHER *****
This is called a cleft sentence. Check out this page for more information.

Student or Learner
Could anybody please explain why the following sentence is correct?
"It was the pictures that he loved."
I have been unable to find anything about this either in my grammar books or on the internet.
Thanks a lot for your help on this.
I've checked out the page and found a helpful description about these types of sentences, however it says that clauses in a cleft sentence are linked by is/was, there are no examples with plural nouns/subjects + is/was combination.
Could you please tell me whether the followings are correct or not?
(My brothers bought a new house from our friends last Saturday.)
It was my brothers who bought a new house from our friends last Saturday.
(Mary and Jim work harder than anybody else in our office.)
Mary and Jim is the person who work harder than anybody else in our office.
(I enjoyed music and ballet most of all.)
Music and ballet was that I enjoyed the most.
(Jewels are hidden under the floor at 20 and 22 Main Street.)
The places where the jewels are hidden is at 20 and 22 Main Street.
Thank you in advance.