Sting follow means that the limbs remain a little bent even when the string is removed.
String follow can be designed into a bow. Or it can be a result of poor design, poor wood, poor construction and is a result of wood damage.
If it is designed, it can be an attribute, within reason.
If it the result of excessive wood damage, it can be a detriment to peformance.
Anything up to 2" of string follow does not bother me. More than that and the bow seems sluggish and slow.
A bow with some follow seems to be a sweeter shooter and is significantly easier to string.