Each garment was worn to atone for a particular sin that Bnai Israel committed:
Every Kohan that served in the temple wore four garments made of white linen- bigdey kohan hedyot-
1. the skirt- kesones- was worn to atone for the murders committed which were not punishable by the Bait Din, because two witnesses were not present, so to, Hashem punished the entire nation for it. also, the skirt was worn to atone for the sin of mixing wool and linen- sha’atniz.
2. the breeches- michnasayim- atoned for the immoratlity amongst Bnai Israel.
3. the belt- avnait- this was worn over the heart and atoned for improper thoughts of the heart. The gematria of the heart- lev- numerical value- was 32 (lamed 30 + bet 2 =32) so to, Hashem commanded that the belt be 32 amot long.
4. the turban-migba’as- atoned for arrogance that Bnai Israel had. Hashem said, “Let the headdress that is worn on the Kohan’s head atone for the sin of holding the head too high.”
They also had four garments made of gold- bigday zahav
1. the mantle- me’il- atoned for the sins of lashon hara spoken in public- speaking ill of people.
2. the apron- aifod- atoned for the sin of idolatry. Those who commited idolatry would wear an apron like robe, so to, the Kohans would wear this apron to atone for the idolator’s sins.
3. the chosed- the brestplate- was worn over the heart and atoned for the sin of perverted judgment, because false judgment radiates from the heart, not one’s intellect (brain).
4. tziz- the head plate- was worn on the Kohan’s forehead to atone for chutzpah- brazenness- and to atone for any blasphemy.