"It's not that easy" / "I don't play Facebook that much"
vs
"It's not easy" / "I don't play Facebook much"
What's the difference??
"It's not that easy" / "I don't play Facebook that much"
vs
"It's not easy" / "I don't play Facebook much"
What's the difference??
This that in your sentences is an adverb, and it's mainly spoken.
Usually, you can understand it as so or very.
So the meanings of your sentences with and without that are not quite the same.
It's not easy. -- This simply means that it's not easy.
It's not that easy. -- This means that it's not so easy or not very easy.
Also often enough, that the adverb is used in context to refer back to the degree (or size or amount) that expressed or expected by another. So, in some contexts, it can be understood either way, i.e. it's not very easy/much/often, or it's not as easy/much/often as the conversation partner might be thinking.
Compare:
I don't play Facebook much. -- A plain statement.
with:
I've heard that you use Facebook 12 hours a day, every day.
I don't play Facebook that much!
(An emphasis that you don't use Facebook as much or as often as the other expects.)
Here is the definition of the adverb that as given by the Oxford dictionary:
that
adverb
[as submodifier]1 To such a degree; so:
'I wouldn’t go that far'
1.1 Used with a gesture to indicate size:
'it was that big, perhaps even bigger'
1.2 informal Very:
'I couldn’t get out of the house fast enough, I was that embarrassed!'
It's not easy.
means it is difficult, and not easy.
It's not that easy.
means it's not so/very easy, OR it's not as easy as some information suggests. Example:
Mark said it's a snap.
Nah.. it's not that easy!
http://www.oxfordlearnersdictionaries.com/definition/english/that_4 - that as adverb.
You can replace this "that" by "so". Often you can explain this use by "in that degree".