Not able to make out the code

DATA: LV_SDATE TYPE D,

LV_EDATE TYPE D,

LO_PERIOD TYPE REF TO YFI7G_GET_PERIOD.

CLEAR TVARV.

CLEAR LV_SDATE.

SELECT SINGLE * FROM TVARV WHERE NAME = 'DATES_OF_CURR_PERIOD'

AND TYPE = 'S'

AND NUMB = 0.

IF SY-SUBRC = 0.

CREATE OBJECT LO_PERIOD

EXPORTING

IV_PERIV = 'N4'

EXCEPTIONS

OTHERS = 1.

IF SY-SUBRC = 0.

CALL METHOD LO_PERIOD->GET_PERIOD_DATES

IMPORTING

OV_SDATE = LV_SDATE

OV_EDATE = LV_EDATE.

//

In the above code I am not able to make out the meaning of following code

SELECT SINGLE * FROM TVARV WHERE NAME = 'DATES_OF_CURR_PERIOD'

AND TYPE = 'S'

AND NUMB = 0.

and

CREATE OBJECT LO_PERIOD

EXPORTING

IV_PERIV = 'N4'

EXCEPTIONS

OTHERS = 1.

IF SY-SUBRC = 0.

CALL METHOD LO_PERIOD->GET_PERIOD_DATES