Wow. Someone is using old software, somewhere.

That's an old Microsoft Works document and I don't believe there is "an app for that" as Microsoft discontinued the software in 2010 (so I don't believe any app would have been developed to read it).
So, you'll have to use a computer to read it or convert that file to either a Microsoft Word file (.doc/.docx) or a text file. for. What I read, the current versions of Microsoft Word can read the wps file. Then, once it's opened, you can save it to a "regular" Word document so you can view it on the iPad. That's if you have a PC with Microsoft Word...
For people with Macs, it's a more difficult story. The Macintosh version of Microsoft works was also discontinued, so you probably can't open/convert it using Works for Mac. But, again from what I read, if you have Mac OS X and a program called NeoOffice (v2.2. or later), then you can open the file.
That's about it. Or, you can ask the sender of the file to change it to a Word document so you don't have to do all the conversion for you. Other than that, that's all I got. Good luck.
Marilyn