These pillars are called stone pens, they are usually erected outside the ancestral house. They are rewarded to commemorate the Hakka scholars of passing the Imperial exams . The pillars ranging from 7-8 meteres to 10 metres were inscribed with the scholar’s name and the posts in the office as well as the surname. They are usually made out of marble or granite. the motifs on the body the pillars are auspicious beast auspicious bird design relief. These pillars erected served as glorying bringing to a family clan as well as served as encouragement for the next generation.
In a metaphorical way, the stone pencils pointing upwards, liken a brush painting , using the sky as a canvas as if to announce the noblity to the heavens above.
Extracted from http://www.hakkasky.cc/wiki/doc-view-575.html , translated with aid of babel fish