Thanks for the quick reply John. The point of the hreflang tag is to tell search engines the targeted language/country for a page. It's a hint about which country's search engine is appropriate. For example, Google has 25 English speaking search engines. Very importantly, it prevents penalties for duplicate content.

For my site most of the pages are identical, but there may be variations such as pricing, so the URL structure is something like:
mysite.com/en-us/producta for English in the US and pricing in dollars
mysite.com/en-in/producta for English in India and pricing in rupees
mysite.com/es-us/producta for Spanish in the US and pricing in dollars

Hreflang was created to simplify international SEO, and without it, international SEO is infinitely harder.