Is this the same installation you had from last year, or did you download a new one and install it recently? If it is, go to brave.com and download the installer.
Also, do you have an antivirus software installed? There have been issues with antivirus software preventing people from opening Brave in the past.
You might have to do a complete wipe of Brave from you mac for it to work. Uninstall Brave, delete any residual files from the system, then redownload the installer.