I need to work with Open Type Fonts only, as it is mandatory by my company. I used Open Sans, which is google font, and even though it says it's an Open Type font, when you click on the additional info, it says it is True Type Flavored? What does that mean?
The Open Type format is, put simply, a standard "wrapper" for font information. The font information itself, i.e. the font outlines, can be either Truetype or CFF/Postscript, which use different kids of curves (different mathematical ways to define the curves). Truetype flavored means the outlines are in truetype format.
More information on the OpenType format.