It depends on what type they are. Standard .ttf fonts can be copied over as is and used the same as any other font in OS X. You can also use Windows Type 1 PostScript font in one particular way. The Adobe applications (Photoshop, Illustrator, InDesign), starting with the CS2 suite, can read these fonts. Place them in the /Library/Application Support/Adobe/Fonts/ folder and you will be able to use Windows Type 1 PostScript fonts with the Adobe programs. This is the ONLY place this will work. All other Mac applications won't have a clue what to do with the paired .pfb and .pfm files. If there is no folder named "Fonts" at the location I noted, simply create it.
PC Type 1 PostScript fonts are paired. Each individual font typeface has both a .pfm and .pfb file. If either one is missing, they won't work. Make sure you place both into the same folder. The file name before the period will be identical, followed by one each of the suffixes named above. Two examples:
SIG
___.PFB
SIG
___.PFM
QSAO
__.PFB
QSAO
__.PFM