Functions as a determiner, very similar to English 'this kind of'. The noun directly follows: 这类问题 ('this kind of problem'), 这类人 ('this kind of person'). No 的 between 类 and the noun.
mistakes
Distinguish from 这种 zhè zhǒng ('this kind' — slightly more concrete/individual) and 这些 zhè xiē ('these'). 这类 emphasizes a category; 这些 just points to a plural set.