加 (jiā, 'add') + 血 (xuè, 'blood' = HP). Synonym 回血 (huíxuè, 'restore HP'). The healer role itself is called 奶 (nǎi, 'milk' — feeding teammates) or 奶妈 (nǎimā, 'wet nurse'). 血量 (xuèliàng) and 血条 (xuètiáo, HP bar) round out the vocabulary.
culture
血 = 'blood' is universal Chinese gaming shorthand for HP, mirroring how MP becomes 蓝 (lán, blue) — based on the standard red HP bar / blue MP bar UI convention. So 加血 = restore HP, 加蓝 = restore MP.
