You can use a third-party BD drive to read and write data discs. However, there is no built-in software to play video BD's, even if you have a drive that can read them. I don't know whether there is now any third-party software that can play those discs; the last time I remember checking, there was not. It's technically (but not legally) possible to convert BD's to a format that can play natively on the Mac, but that subject can't be discussed within the terms of use of this site.
The copy protection on BD's won't allow them to be played at full resolution on an external display without end-to-end hardware copy protection (HDCP) in the graphics subsystem.