What is the meaning of ?

The hiragana syllable (ri). Its equivalent in katakana is (ri). It is the fortieth syllable in the gojūon order; its position is (ra-gyō i-dan, row ra, section i).

Used to form the stative of verbs: did; have done

adverb-forming suffix following some onomatopoeias or ideophones

short for 了解 (ryōkai, understand)

Source: wiktionary.org