can some one explain me the function of the below code in specific

| eval created_upper_token=if("$time_token.latest$"="" OR like("$time_token.latest$","%now%"),"@s","$time_token.latest$") | eval created_lower_token=if("$time_token.earliest$"="",0,"$time_token.earliest$") | replace "rt*" with * in created_upper_token | replace "rt*" with * in created_lower_token | eval created_lower_bound = if(isnum(created_lower_token), created_lower_token, relative_time(now(),created_lower_token)) | eval created_upper_bound = if(isnum(created_upper_token), created_upper_token, relative_time(now(),created_upper_token)) | where order_date >= created_lower_bound AND order_date <= created_upper_bound|