Can someone please FULLY explain the ACCESS and PACKAGE_ACCESS fields

Hi,
DT 6.5.8 WP 3.9.1

After a .csv export would like to FULLY understand the meaning of the ACCESS field.

For example:
my access field is: s:19:”a:1:{i:0;s:2:”99″;}”;

my package_access is: s:42:”s:34:”s:26:”s:18:”a:1:{i:0;s:1:”0″;}”;”;”;”;

We will conduct a huge import and would like to make sure we fully understand each parameter/string.

Thanks!