What is the meaning of ?

The hiragana syllable (ru). Its equivalent in katakana is (ru). It is the forty-first syllable in the gojūon order; its position is (ra-gyō u-dan, row ra, section u).

A general method to form verbs (as a godan katsuyō verb). Much less productive than 〜する (-suru, to do).

the present progressive: to be doing

Classical Japanese form of れる (-reru, passive suffix)

adnominal of (-ri)

Source: wiktionary.org