I would start with saying - read the Calibre manual (Standard Verification Rule Format Manual) - there it is described.
Then I would say - if you have DRC/LVS/PEX decks from manufacturer - do not change it - it will just screw you up unless you really know what you are doing.
Precision is ratio of database units to user units. Default is 1000 which usualy translates to 1000 database user units per 1 um.
Resolution is mainly used for offgrid checks - if it says 1 then it says that database grid is 0.001 dbu
Usualy in deck is defined Unit Length - which specifies user units used in the deck. options are: u; mil, mm, cm, inch, m
- so don't change it unless you have to. Whole deck is written base don those definitions and if you change it / override the deck specified values with option form values your lvs will most probably fail.