Benefit of Sub Domain

Organized Content - Subdomain helps to organize content in better way, for different section you can make a different website. It increase user experience.
Enhance Security - Using Subdomain can improve website security. You can secure sensitive data on secondary website.
Better for SEO - By subdomain we can specific keywords it help to boost ranking on SERP. Targeting niche will help in long run to get on top of SERP.
Customization - You can customize website according to language, content, region, gender, etc.

Sumit