The passage Typing is one of the rounds which is carried out by the MNC companies. To clear this round you must have both Typing skill as well as grammatical knowledge. And you also should have some imagination skills. Because, the questions of the passage typing may be a text or an image.
The text-based questions consist of the question in the form of text. For example  “Urbanization boon or bane”. You have to write the passage about this topic.
And the image based questions consist of an image which gives some meaning. And you have to use your imagination skills to develop a story based upon the internal hidden meaning of that image.

Some of the basic rules of passage typing is,

You have to type minimum number of words mentioned by the company. It may vary from one company to another company. Normally, it is minimum 200 words.
You have to complete the entire story within the given time(1/2 hour or 1 hour)
And there should not any grammatical mistakes or spelling mistakes.
Some of the companies also consider the number of times you used backspaces to rectify your spelling mistakes.
You should type at least three passages. 
First passage     - Introduction
Second passage - Concept about the given topic
Third passage    - Conclusion