Here's your code in a better format with comments:
//connect to the database server
$conn = mysql_connect("localhost","project","Pass") or die("Cannot connect to database server");
//select the database
mysql_select_db("vehicle", $conn) or die("broke");
//declare an SQL statement
$sql="(INSERT INTO employee(f_name,l_name,v_id,job_cd,dest,out_date,in_date) VALUES('$f_name','$l_name','$v_id','$job_cd','$dest','$out_date','$in_date')";
//get the last inserted id from the query sent
$conf_num = mysql_insert_id();
//print this id
print("$conf_num");
now, on which line is the query sent?
There is no mysql_query($sql), only a string that appears to be an SQL query, but isnt used at all.