The range stat just tells you what range most of the Stand's attacks will be. For example, Red Garland is S, which tells you that most of Red Garland's attacks will be in the S range.
Quick explanation about range from the Introduction page:
In JoJo's Bizarre Adventure, each Stand has a 'range' attribute limiting the distance at which they can manifest. In 7th Stand User, each Stand and many attack moves also have individual ranges:
Short-range (S) attacks have the highest power output, but do little damage to enemies that are far away.
Mid-range (M) attacks have a reliable damage output regardless of range.
Long-range (L) attacks have the lowest power output, but can hit enemies at any range.
For example, attacking an enemy at long range with a short-range attack will do nearly no damage at all. Attacking an enemy at short range with a long-range attack will damage them, but will consume much more SP and won't do nearly as much damage as a short-range attack on the same enemy.
