Basically, a shared inbox enables your team to have access to one mailbox all together. This does not only offer the chance to streamline your support, but it can also help companies without a traditional support channel.
You wonder how? The idea behind it is that everyone can access the incoming emails/tickets, can answer them, pass them on to the responsible person and that they are always assigned to the right contact or company in your CRM. The connected email address does not need to be a support email address, it can also be your info email address or the email address of your administration. Furthermore, the tickets can be used as a means of internal communication to facilitate collaboration.
Check here for the next part on shared inbox: Getting started: How can you get started with shared inbox?