Social control is the set of processes by a society regulates the behavior of its members. All societies must practice social control so as to be able to impose their values on their members. When industrialization started, more forms of social control became available.
Before the Industrial Revolution, more people were their own bosses. They worked for themselves and so were relatively independent. Their behaviors could not be controlled very efficiently.
With industrialization, more people came to work for others, often in large factories and companies. The bosses in such situations could exert much more social control over the common people than ever before. They could essentially force them to wake up at certain times, come to work at certain times, and go home at certain times. In places with "company towns" they could even regulate things like education and religion.
In this way, industrialization allowed industrialists to control common people in ways that had not generally been possible before.