it 在语法上被称为“无意义的宾语”，你可以这样理解，它在这里只是充个数，否则 hate 就没宾语了。非得翻译的话，可以翻译为：那个情况。
而 when 引导时间状语从句，表示你讨厌那个情况时的时间。比如：
I hate it when you lie. 我讨厌你说谎。
也就是：当你说谎时，我很讨厌（那个情况）。但是，一般不把那个情况翻译出来。
I hate it when people cry.
我厌烦别人哭。《牛津高阶英汉双解词典》
I hate it when people accuse us of that
我讨厌别人就那件事指责我们。《柯林斯高阶英汉双解学习词典》
I hate it when my students yes me all the time.
我讨厌我的学生们一味对我附和。
I hate it when people talk about me behind my back.
我讨厌人们在背后议论我。
I hate it when you can't discuss things openly.
我讨厌你不把事情拿到桌面上来谈。
I hate it when people talk with their mouths full.
我讨厌人们一边嘴里满是东西，一边谈话。(说的是餐桌礼仪)
I hate it when you’re gone.
我讨厌你不在我身边。
还有一些动词也是这么用的，常见的有机物动词like, dislike, love, enjoy, prefer, appreciate 等类似句型“主语+及物动词+it+when/if引导的状语从句”：
I dislike it when people talk with their mouths full.
我讨厌人们一边嘴里满是东西，一边谈话。
I like it when spring comes.
我喜欢春天来临的时节。
I'll appreciate it if you could open the window for me.
如果你能帮我打开窗户，我将不胜感激。
I don't like it when you shout at me. 我不喜欢你对我大喊大叫。
I dislike it when you whistle. 我不喜欢你吹口哨。
I don't love it when she tells me how to do things.
我不喜欢她对我做事指手画脚。
I should prefer it if you didn’t go there alone.
我倒希望你不要一个人去哪儿。
I like it when she reads to us. 我很喜欢她读书给我们听。
I like it when you cook me dinner. 我喜欢你给我做完饭。
I like it when you smile.我喜欢你笑。
I don't like it when you phone me so late at night. 我不喜欢你夜里这么晚给我打电话。
I just love it when you bring me presents! 我就喜欢你送我礼物！
I love it when it rains. 我喜欢下雨天。
I love it when you kiss me goodnight. 我喜欢你给我亲亲晚安。
I hate it when people cry. 我厌烦别人哭。
I hate it when you lie to me. 我讨厌你对我说谎。
I really hate it when you make a mess. 我真的特别讨厌你把事情搞得一团糟。
We hate it when our friends become successful.
我们讨厌朋友成功。
We really appreciate it when she offered to help.
她来帮忙了，我们十分感激。
I would appreciate it very much if you would offer me some suggestions. 如果你能给我提供一些建议，我将十分感激。
还有词组see to，depend on后面都是先接it再接从句。
Can you see to it that the fax goes this afternoon?
你保证今天下午就把传真发出去，行吗？
Please be so kind as to see to it that all the alterations are made at once!
请务必立即执行变更！
Catherine saw to it that the information went directly to Walter.
凯瑟琳确保这条消息直接传达给了沃尔特。
You may depend on it that he will help you.
你可以指望他来帮助你。
You may depend on it that he will attend the meeting in time.
你可以寄希望于他能够及时赶到出席这个会议。
Can we depend on it that you are able to do it well?
我们能相信你有把握做好这件事吗？
Yon may depend on it that they will support you.
你可以指望他们会支持你的。