释义 is a verb‑object compound (离合词) meaning 'to explain the meaning (of a word, text, passage, etc.)'. The verb 释 ('explain') and the object 义 ('meaning') can separate when you add a measure word, duration, or complement: e.g. 释了一次义 ('explained the meaning once'), 释了半天义 ('spent a long time explaining the meaning'). Use it as a single unit in most everyday sentences, and split it when you need to count or describe the action.