This is the opposite of Quora where respondents actually cite sources. Here, it's a free for all, opinion-fest, and most of the advice given is either highly questionable or downright dangerous to the uninitiated.
Yahoo answers is a site where anyone with an account can ask or answer a question. It can be useful to get some info, but some people on this site (like every other website) can be stupid or misinformed, so check multiple answers. Trolls can also post on here an make rude or mean comments or nasty questions. Many questions have to do with sexual health or relationships, so kids should not be on this. Instead kids should ask their parents for solutions to their problems, and not the internet.
Although it can be used for help in certain less known subjects, on the topic of medicine, religion, or politics it is impossible to get a reliable answer. It is unusually high in its subject to "trolls" as well as questions posted solely to hear what someone wants to hear (see the politics section). Do not use for solid advice.