What is the punishment for someone hiding a runaway teen?

The punishment for someone hiding a runaway person, and whether any punishment applies, depends on what a person of any age is running from, whether there is a crime involved, and if so, on the nature and severity of the crime.

If no crime is involved, the age of the teen becomes more important, as well as the reasons the young person needs to hide, and from whom, and the motives and actions of the person hiding or offering shelter to the person seeking refuge.

If the person seeking refuge is underage, there will be special focus directed towards the person hiding the youngster, and, again, towards their actions and motives, than if the teenager is of age.

'Underage' is defined differently from country to country and from region to region within countries; local legislation also differs, sometimes widely, between areas.

If it's found that a crime is involved, and the case comes to court (most don't) the decision of the court hearing the case affects any sentencing, as application of local laws varies from court to court as well as from area to area.

As with all legal matters, each case is unique. It is wrong and can be dangerous to rely on information which doesn't come from a qualified person in possession of all the facts relating to the case in question. Unqualified advice can, and frequently does, lead people into actions which land them in more trouble than they started with!

There are avenues by which a person unable to afford legal advice can seek advice; you can contact your local Department of Justice (which might go under other, similar, names) to discover who to contact.