What does section $8($d$)$ of the Taft$-$Hartley Act explain about collective bargaining?

What does section $8($d$)$ of the Taft$-$Hartley Act explain about collective bargaining?

No party can request for a written contract incorporating agreement reached.

To bargain collectively is the performance of the mutual obligation of the employer and representative of the employees.

Employer and union are prohibited from bargaining collectively on any topic except wages and hours.

Each party is obligated to reach an agreement or make a concession.