How to use left join with Where clause
You might try this, however as I do not have any understanding of your schema, the result might not be what you search for.

select
  leave_detail_id
  ,emp_id
  ,Employee_Name
  ,leave_type
  ,leave_name
  ,sum(leave_total_days) total_leave
  ,leave_current_status_id
from employee emp
left join  tbl_emp_leave_details eld
  ON emp.PK = eld.emp_id
left join tbl_leave_types lt
  ON lt.leave_id = eld.leave_type
  and leave_current_status_id = 1
  and leave_start_date &gt;= '01-07-2019'
  and leave_end_date &lt;= '31-07-2019'
group by 
  leave_detail_id
  ,emp_id
  ,Employee_Name
  ,leave_type
  ,leave_name
  ,leave_current_status_id