What does this mean?

I could never understand this:

Stat Name 12 + 2 +2

Whats the two +2's and why not write:

Sta Name 16?? thats essentially what it will be no?

I think you probably saw something like 12 +1 +2, that means 12 from the attribute points, +1 from the head gear, +2 from a rune.
Head pieces have a natural +1 for an attribute.

oh ok. that makes sense. so its attr + head + rune?

Exactly.
So in a build as the follow:
Expertise: 12 +1 +2
Marksmanship: 12 +2

means that you need to use the expertise rune in the head piece.

Perhaps a convention may have set in, but some people write attr + rune + headgear bonus. It's 100% unambiguous either way.

PS: To answer your original question as to why they don't just write 16, it's because it's not necessarily clear when you're running 3 or 4 attributes. For example, look at these paragon attributes:

14 Spear Mastery
12 Command
8 Leadership
10 Healing Prayers

Which attribute is the headgear bonus for? What runes are minor/major/superior? It's certainly not obvious, and it'd probably take a fair amount of effort to figure it out if you're not highly familiar with the system.