In Android, just like in Windows, if you want to view a document containing a non-Unicode font, the font must be installed in the system first. Now the process of installing a font in Android is almost the same as that of Windows. Just like in Windows we have to copy the .ttf file of the font and paste it in Fonts folder (Directory). But unlike Windows, the system folders in Android are read only. You could copy files from that folder but cannot paste or delete any files in this folder. This is a security feature of Android.
However, there is a way to overcome this problem and that is to root your device. To root your device means, you gain control of your device, such as the Linux root or Windows Administrator, you can now modify the system folder. The process to root your device is a technical process which involves a little risk that the device could be damaged (only during the process to root, not after that). The procedure to root every phone or tablet model could be found on Google, you just have to type your device's model number in Google search.
I Know How to Root a Device
Well if you already know how to root your device, so let us see how a font should be installed in it. Use a root file manager for this process. There are many good Apps, such as Root Explorer or ES File Explorer, that you could download and use. First you have to copy the required font files in your device's memory card or download directly from the internet to your device. Now copy it and using the above App paste it in your device’s /system/fonts Directory. The font will be installed. Now after this font is installed you could see any document containing this font; that is you are now able to read documents in Hindi.
My device is not root, what do I do?
If your device is not root and you are also not willing to take the risk to root your device, then the simple solution is to convert the document containing Hindi fonts from a word file into a PDF file. After you saved a document as a PDF file, you can read that Hindi document on your Android device. However, now you cannot modify that file, you could only read the file.
Now if you ask whether we could create an application to view the word documents (or any other office file) containing Hindi fonts without installing the font? Well the simple answer is yes; such an application could be created. But it will serve as a wrapper and only enable you to view just that particular Word file. Also you could only read that file on that App and you could not modify or change anything in that document. To edit it you will have to open that file in an office suite.
Photo Source: Wikipedia