Do you know if Google already know how to read URLswith /#/

I don't see why not. The question is whether they will interpret it as an URL for SERP purposes, or if they will send everyone to example.com/ (the part before the #). They do sometimes link to fragments, but all the time ...?

Is this a site that already exists, or a change you're thinking about making? I assume you've got a reason for using a less-common URL pattern.