Hi @rohitmishra1692, thanks for messaging the Community!
If you're interested in subscribing to a paid Dropbox plan, you can do so from here, which will also tell you about the different plans available. Depending on your requirements, each plan varies in what they offer.
As to Dropbox itself, it is primarily a service to sync your files to the site and to other connected devices, allowing the most up-to-date file to sync on any device. You can read more about its features here.
Hope this helps!