Some PTVL screenshots: http://imgur.com/a/MJ4TI#0
First, here is the link to the PTVL thread: http://forum.kodi.tv/showthread.php?tid=169032
There is a bit of a learning curve to PTVL. It has an "auto-tune" feature that is designed to simplify the process of setting up your "channels", but to really customize it you may want to dig into some XML files to configure your channels and TV Guide setup. PTVL is only at version 0.59 so far, so it isn't perfect, but I absolutely love what it does and I use it to run all of the TVs in my home.
HDHomeRun is a device that allows you to capture Live TV, and share it over your network via UPnP/DLNA (So you can watch your TV channels on a computer, laptop, or tablet. On a computer you can then set up your own DVR if you want. If you want to capture Cable TV, then you need the HDHomeRun Prime, and you will need to get a "cable card" from your cable provider. Some providers will give you one for free, others may charge a small monthly fee. Setting up the CableCard may require some support from your Cable Provider to activate it. If you don't pay for the excess garbage on cable TV and just want access to your local over-the-air channels, you don't need the HDHomeRun Prime, and can go with the smaller/cheaper HDHomeRun devices, but you will need to buy an antenna separately that plugs in the HDHomeRun device. I believe the Prime can also accept an antenna. The Woot price is pretty good so you may want to just go with that.
PTVL is a plugin for Kodi that creates a TV-like interface. That means you have "channels" of media, and you can surf through these channels just like you do with regular TV or Cable. PTVL can accept all sorts of sources to build channels- media saved on your hard drive, content from many other Kodi plugins or add ons, YouTube channels, Internet streams, HDHomeRun streams, and so on. There are all kinds of different options for these channels. You can schedule specific shows to show at a specific time of day, or setup a channel that auto-pauses when you are not watching (nice if you want to watch a season in order, though I have had some issues with that setting) PTVL provides an "EPG"- that is an Electronic Program Guide, similar to what you would see when browsing channels on a Cable or Satellite service. This EPG is even skin-able, so users have created skins that look and feel just like Comcast or DirecTV, as well as other nice custom EPGs.
To answer your question- if you would like a way to access your TV channels on a device other than your TV- (computer, laptop, tablet) then yes you should get the HDHomeRun.
tl;dr:
Using PTVL with an HDHomeRun is the absolute best way to merge the worlds of broadcast or cable television with internet media (other kodi plugins, downloaded media, youtube) all into one channel-surfable experience. If you have any other questions ask away and I'll offer the info I can, or you can check out the PTVL Kodi Forum linked above, but there is a LOT of traffic on that thread (its 500+ pages at this point) so I've found it is easy for questions to get lost and buried there.