Only if it's been formatted as NTFS on the Windows PC - then it will
read-only on the Mac. You won't be able to write to it but you can drag files off it onto your Mac to edit them.
If it's formatted as FAT - which most new drives seem to be these days - then you can read
and write to it on your Mac.
Neither NTFS or FAT formats won't make any difference to the files on there or the drive itself. If you do want to enable writing to NTFS drives, you can buy 3rd party software such as
'Paragon NTFS for Mac' to install on your Mac to enable it. Again, none of this should affect the data on there at the moment.