Dataframe to Postgresql without SQLAlchemy

I want to write pandas dataframe to postgresql table. But I dont understand that "INSERT INTO %s(%s) VALUES %%s" % (table, cols) syntax. There are 9 columns value in my dataframe (pm2_5_ugpm3, PM4_ugpm3, PM10_ugpm3, Pressure, Temperature, Humidity, NO2, O3, time)

def execute_values(conn, datafrm, table):
    
    # Creating a list of tupples from the dataframe values
    tpls = [tuple(x) for x in datafrm.to_numpy()]
    
    # dataframe columns with Comma-separated
    cols = ','.join(list(datafrm.columns))
    
    # SQL query to execute
    sql = "INSERT INTO %s(%s) VALUES %%s" % (table, cols)
    a = conn.cursor()
    try:
        extras.execute_values(a, sql, tpls)
        conn.commit()
        print("Data inserted using execute_values() successfully..")
    except (Exception, psycopg2.DatabaseError) as err:
        # pass exception to function
        print(str(err))
        cursor.close()