全く～ない is an expression that combines the 副詞（ふくし） (adverb) 全（まった）く, with a phrase that uses another word in its ない form. It is often translated as ‘not at all (A)’. Literally, it is closer to ‘completely not (A)’, or ‘entirely not (A)’, coming from the kanji 全（ぜん）’s meaning of ‘whole’.
Like many other adverbs, まったく may be used at the beginning of a sentence, or directly before the word that it is describing as being ‘not at all’ (A).

• この子（こ）は全（まった）く吠（ほ）えないですよ。
  This dog does not bark at all. (子（こ） may sometimes be used about pets, if it is obvious what is being discussed)
• あんたに褒（ほ）められても全（まった）く嬉（うれ）しくない。
  Even if I did get complimented by you, it wouldn’t make me happy at all.
• 店員（てんいん）さんが「この扇風機（せんぷうき）は静（しず）かですよ」って言（い）ったから買（か）ったのに、全（まった）く静（しず）かじゃない。
  The shopkeeper said 'This fan is very quiet', so I bought it. However, it was not quiet at all.
• 全（まった）く筋肉（きんにく）がないので私（わたし）だけでは持（も）てません。
  I don't have any muscles at all, so I can't carry this by myself.

It is common to see this expression using both the kanji form, and plain hiragana form of 全（まった）く, so both should be learned early.