SLA Customization

Is it possible to have a custom Ticket Selector in the SLA. For example, currently there are 3 options in the Priority section (1 low, 2 medium, 3 high). Could these fields be customized to say something different, such as (When possible, Unable to do my job, etc.). I am not a programmer, but if someone is able to tell me how to adjust the code, that works too.