限量 is a separable verb (离合词) meaning 'to limit the quantity of something.' It commonly appears attributively in set phrases like 限量版 ('limited edition'). As a v.o. (verb-object), the two syllables can be split—for example, 限了量 ('set a limit')—though in practice the split form is less frequent than with other separable verbs. You can also use it in the pattern 限量 + noun to describe limited-run products.