Ven. Bhikkhu Bodhi writes:
"Bhava, in MLDB, was translated “being.” In seeking an alternative, I had first experimented with “becoming,” but when the shortcomings in this choice were pointed out to me I decided to return to “existence,” used in my earlier translations. Bhava, however, is not “existence” in the sense of the most universal ontological category, that which is shared by everything from the dishes in the kitchen sink to the numbers in a mathematical equation. Existence in the latter sense is covered by the verb atthi and the abstract noun atthitā. Bhava is concrete sentient existence in one of the three realms of existence posited by Buddhist cosmology, a span of life beginning with conception and ending in death. In the formula of dependent origination it is understood to mean both (i) the active side of life that produces rebirth into a particular mode of sentient existence, in other words rebirth-producing kamma; and (ii) the mode of sentient existence that results from such activity."
http://www.wisdompubs.org/book/connecte ... troduction
A good and clear example of 'bhava' as a countable span of life can be found in Ratana sutta:"Unfortunately, atthita and bhava both had to be rendered by "existence," which obscures the fact that in Pali they are derived from different roots. While atthita is the notion of existence in the abstract, bhava is concrete individual existence in one or another of the three realms. For the sake of marking the difference, bhava might have been rendered "being," but this English word is too likely to suggest "Being," the absolute object of philosophical speculation. It does not sufficiently convey the sense of concreteness intrinsic to bhava."
Metta, Dmytro232. Ye ariyasaccāni vibhāvayanti
Kiñcāpi te honti bhusappamattā
Na te bhavaṃ aṭṭhamaṃ ādiyanti,
Idampi saṅghe ratanaṃ paṇītaṃ
Etena saccena suvatthi hotu.
Those who have seen clearly the noble truths
well-taught by the one of deep discernment —
regardless of what [later] might make them heedless —
will come to no eighth state of becoming.
This, too, is an exquisite treasure in the Sangha.
By this truth may there be well-being.
http://www.accesstoinsight.org/tipitaka ... .than.html