I've seen this written at various places say shop entrances, home entrances, etc...

These terms are generally written along with lord Ganesha's image.  Not only this, it is also written on Marriage Invitation cards, and Diwali greetings.

The terms are often associated with swastika symbol *(well, most of the time)*

So why they write the terms Shubh which means *(auspiciousness)* and Labh means *(Profit)*!

![Shubh Labh with Swastika symbol][1]

<sup>Image Credits : [zns.india.com][2]</sup>

  [1]: http://i.stack.imgur.com/odqh7.jpg
  [2]: http://zns.india.com/