这个what=that which=the thing which, 引导名词性从句（现代语法称为名词性关系分句），这个what从句相当于一个特指名词后接限制性定语从句。因此，six times what it was before liberation=six times the amount that it was before liberation. 其中人称代词it指代主句中的output，关系代词that指代先行词the amount并在定语从句中作表语。

译文：现在的产量是解放前的六倍。

Output is now six times what it was before liberation.

参考译文：现在产量是解放前的产量的六倍之多。

now six times  what 是表示比较倍数结构

what 代替的the amount that 这是表语从句

以上是关于倍数表达

上面使用倍数结构为“… times + what 从句”
The length of the road is four times what it was three years ago. 

这条路的长度是三年前的 4 倍。
The price of the meat is twice what it was last year. 

肉价是去年的两倍。

除了以上结构表达之外，还有一下几种表达。供提问者参考,希望对你有帮助。

【一】用 times 表示倍数（一般限于包括基数在内三倍或三倍以上的数。表示两倍的数，一般用 twice ）。其句式有：
【1】 “… times ＋形容词 / 副词的比较级＋ than …”
Line AB is three times longer than line CD. 

线段 AB 是（线段） CD 的三倍长。
This hall is five times bigger than our classroom. 

这个大厅比我们的教室大 5 倍。

【2】“… times +as + 形容词 / 副词的原级＋ as …”
This table is three times as long as that one. 

这张桌子是那张桌子的三倍长。
This dictionary is five times as thick as the one you borrowed from the library.
这本词典的厚度是你从图书馆借的那本（厚度）的 5 倍。

【3】 “… times + the + 名词（如： size， height， weight， length， width 等）＋ of …”
The earth is 49 times the size of the moon. 

地球的体积是月球的 49 倍。
This river is three times the depth of that one. 

这条河是那条河的三倍深。

【4】“… times + more ＋名词＋ than …”
He earns five times more money than he did ten years ago.

他现在挣的钱比十年前挣的多 5 倍。
There are twice more students in our class than in theirs.

我们班的学生人数比他们班多两倍。

【5】“… times +as many （或 much ）＋名词＋ as …”
We've produced twice as much cotton this year as （ we did ） ten years ago.
今年我们生产的棉花比十年前多了一倍。（汉语中的多一倍实际上也指两倍一样多。）
He has got three times as many books as his sister.

他拥有的书的数量是他妹妹的 3 倍。

【6】“… times + what 从句”
The length of the road is four times what it was three years ago.

这条路的长度是三年前的 4 倍。
The price of the meat is twice what it was last year.

肉价是去年的两倍。
【7】  “… times + up on （或 over ）…”
The size of the sun is a million times over that of the earth.

太阳的体积比地球的体积大一百万倍。
He is three times up on your age. 

他的年龄是你的4倍（或：比你的年龄大3倍）。

 【8】“… +by + … times ”
Compared with last year， our coal output has increased by three times.

与去年相比，我们的煤产量增长了3倍。
His speed is faster than mine by four times. 

他的速度比我的快 4 倍。

【9】 “… times + compared with ＋被比较对象”
The number of the students in our school has increased three times compared with 1980.
我们学校的学生人数比 1980 年增加了3倍。

【10】 “… times + that of + 被比较对象”
In this workshop the output of July was 3.5 times that of January.

这个车间七月份的产量是元月份的 3.5 倍。

【二】用分数、百分数表示倍数。
The box is one-third bigger than that one. 

这个盒子比那个盒子大三分之一。
Last year the output value of industry was 59 percent higher than that of 1976. 去年工业产值比 1976 年增长了 59 ％。
My command of English is not half so good as yours. 

我英语掌握得还不及你的一半儿好。
【三】用 again （一倍），double （两倍），triple （三倍），fourfold （四倍）等词表示倍数。
My Aunt is as old again as I am. 

我姑姑的年龄比我大一倍。
The top-brand clothes are often sold as double the normal price here. 

这里名牌衣服的售价经常比正常的售价高一倍。
The new work procedure tripled the output. 

新工艺使产量增加两倍。
The output of grain increased fourfold. 

粮食产量增加了三倍。

what引导名词性从句的五种用法

【一】用法归纳

【1】表示“……的东西或事情”相当于the things that…：

They’ve done what they can to help her. 

他们已经尽力帮助了她。

He saves what he earns. 

他赚多少，积蓄多少。

What Mary is is the secretary. 

玛丽的职务是秘书。

【2】表示“……的人或的样子” 相当于the person that…。如：

He is no longer what he was. 他已经不是以前的那个样子。

He is what is generally called a traitor. 他就是人们通常所说的叛徒。

Who is it that has made Fred what he is now? 是谁把弗雷德培养成现在这个样子的？

【3】. 表示“……的数量或数目” 相当于the amount/number that…。

Our income is now double what it was ten years ago. 

我们现在的收入是10年前的两倍。

The number of the students in our school is ten times what it was before liberation. 

现在我校学生的数量是解放前的10倍。

【4】. 表示“……的时间”相当于the time that…

After what seemed like hours he came out with a bitter smile.

似乎过了几个小时他才苦笑着出来。

The young girl was too frightened to speak, standing there for what seemed like hours. 小女孩吓得不敢说话，在那儿站了几个小时。

【5】. 表示“……的地方”相当于the place that…。如：

This is what they call Salt Lake City. 这就是他们称为盐湖城的地方。

In 1492, Columbus reached what is now called America. 1492年哥伦布到达了现在所称的美洲大陆。

What is now the North Sahara Desert was once a civilized world.

现在的撒哈拉沙漠的北部曾经是一个文明世界。

【二】用法说明

【1】 这样用的what相当于“先行词+关系代词”，所以其前不能有先行词：

你喜欢什么就拿什么吧。

正：You can have what you like. / You can have everything (that) you like.

误：You can have everything what you like.

【2】有时what 可用作限定词，其后修饰一个名词：

I gave him what books I had. 我把我所有的书都给他了。

He gave me what money he had about him. 他把身边带有的钱全给了我。

 【3】What 后的名词可以是复数名词或不可数名词，但通常不能是单数可数名词：

误：I gave him what book I had.

【4】 What后接不可数名词时，有时可有little修饰。注意区别：what+不可数名词=所有的都，what little+不可数名词=虽少但全部。如：

I spent what time I had with her.

我所有的时间都是与她一起度过的。

I spent what little time I had with her.

我仅有的一点时间都是与她一起度过的。