It is equivalent to saying:

I has been “a short time” since I last heard from you.

The second sentence is incorrect because…

Awhile means “for a while” which doesn’t work in the sentence. It is equivalent to saying:

It has been “for a while” since I last heard from you.

The Curmudgeon says:

“A while / Awhile

“Grammatically, a while is a noun phrase in which “a” is an article and “while” functions as a noun meaning “a short period of time”; awhile is an adverb meaning “for a while.” In other words, the meaning is the same, but the structure is different: the word awhile has “for” built into its meaning.

“The test of which to use is to consider whether “for a while” may be used in the sentence where we intend to place (or have placed) the word awhile – without changing anything else.

“Examples:

> “I’ll wait here awhile” is correct because we could also say, “I’ll wait here for a while.”

> “I’ll wait here for awhile” is not correct because we have actually used the word for twice, given that awhile = for a while: “I’ll wait here for for a while.”

> “I’ll be there in awhile” is not correct because we would not say, “I’ll be there IN FOR a while.”

> “This may take awhile” is not correct because “This may take for a while” is not idiomatic English.

> “My mother is staying awhile” is correct because we could also say, “My mother is staying for a while.”

“The two-word noun phrase (a while) is probably more often the correct choice than is the one-word adverb (awhile). Certainly, most misuses of a while / awhile involve using awhile where a while is the appropriate construction.”

Other examples: “sit down and stay awhile”; “they settled awhile in Virginia before moving West”; “the baby was quiet for a while”

And just as I thought, the correct use of the word or phrase from ur question would be ‘It has been A WHILE since I last heard from you.’ Because! –A WHILE must be used as a ‘noun phrase’ here NOT as an adverb like in the second sentence…know why?

bcuz here is how the sentence is actually structured: ‘It(::subject) has been(::verb) a ‘NOUN'(::object) since I last heard from you.’ Get it? =)))

Now, an even better sentence to use might be ‘Let’s talk for A WHILE.’ and ‘Let’s talk AWHILE.’ Because now you get to see the difference between the two and their correct usage in a very similar sentence! The word WHILE is a NOUN in the first sentence..because it is preceded by an arcticle duh, right?..let’s make it obvious…it’s like say for example saying.. ‘a dog’ lol; in the same way one can say ‘a while’. (In awhile the a is NOT an article..it’s part of the whole word.. which is pretty obvious, am i right?) So the WHILE in A WHILE is a noun :o) ..joo see? Now, as in the second sentence, AWHILE is an adverb just as one might say ‘Let’s talk quickly.’ or hastily or angrily or w/e lol other adverb you wanna use!!!! Good luck! lol …hope u made sense of all the madness that is English.YAY! lol.

(It’s fun tho :P)

Remember!: An adverb is a word that defines a VERB. It’s like an adjective ..but instead of for a noun..for a verb. An ADverb. =D. SO: In case ur still sorta confused, remember that ..I know you can also say “We waited a while.” and “Let’s talk a while.” But the awhiles in the sentences: “We waited awhile.” and “Let’s talk awhile.” Are only adverbs and thus allowed and correct usage only Because they describe verbs in the sentence..AKA: waited and talk. So that’s why writing “It has been AWHILE…” would NOT be correct. What verb is the would-be adverb describing here??—(It’s Just like saying “It has been quickly.” makes no sense either lmao.) Get it? 🙂 Hope ya did. Cheerio m’lady and best of luck to ya.

it’s almost always a while