The same pin cannot be used simultaneously for uart and debug.
But, the data sheet has a footnote on some pins: "Upon reset, these pins are configured as SW debug alternate functions...".
Meaning: The UART pin function is done by your firmware, *after* reset. In the short time before that, SWD is available, so you can still connect to the MCU under reset, e.g. for flashing or loading a special debug firmware etc... Note that this use of SWD depends also on your board design (pull-ups/downs,...), so read the data sheet carefully and test on a prototype.
If you can avoid that dual pin use: I would avoid it. Look for alternate UART pin function mappings.
hth
KnarfB
