Explanation

Box 1: is
Note: sp_change_log_shipping_primary_database,
Parameter: [ @backup_share = ] 'backup_share'
Is the network path to the backup directory on the primary server. backup_share is nvarchar(500), with no default, and cannot be NULL.
Box 2: 72 hours
4320 minutes is 72 hours.
Note: sp_change_log_shipping_primary_database, Backup_retention_period parameter
@backup_retention_period = ] 'backup_retention_period'
Is the length of time, in minutes, to retain the log backup file in the backup directory on the primary server.
backup_retention_period is int, with no default, and cannot be NULL.
Box 2:
SP_Add_Retcode
Box 3: 24 hours
sp_add_schedule
@freq_type (here 4, which is daily)
A value indicating when a job is to be executed. freq_typeis int, with a default of 0, and can be one of these values.
ValueDescription
1Once
4Daily
8Weekly
16Monthly
32Monthly, relative to freq_interval
64Run when SQLServerAgent service starts
128Run when the computer is idle
@freq_interval = ] freq_interval
The days that a job is executed. freq_interval is int, with a default of 1, and depends on the value of freq_type.
Value of freq_typeEffect on freq_interval
1 (once)freq_interval is unused.
References:
https://docs.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sp-add-schedule-transact-sql