what's the meaning of this onewhich are really convenient during certain times of the year.certain times of the year

what's the meaning of this one
which are really convenient during certain times of the year.
certain times of the year

.这一年的一定时期里,.真的很方便

一年中在肯定的时间里到底是真正有空的？

certain times of the year
一年中的特定时段

一年中特定的时间
一年中的某个时间