Hi awdesh,
By industrial relation we mean a relation between employer and the workers/labour workforce.
The term 'industrial relation' is very wide and includes the provisions of labour labour, personal management, etc.
Having a sound industrial relation is desirable because it safeguards the interest of employer and workers. It ensures a smooth system to enhance the productivity and a cordial work environment. Grievance handling, trade unions, labour laws and their provisions, workers committee are also covered in industrial relations.
I hope after reading you have a fair idea of IR.
All the best