'[Noun] को [verb infinitive ] है' (eg: नेहा को खाना है) is used to mean '[Noun] has to [verb]' (Neha has to eat') or '[Noun] wants to [verb]' (Neha wants to eat) depending on the context.
This construction is somewhat idiomatic and cannot be translated literally into English. If you want, you can think of it as being something like 'To Neha, eating is (wanted/needed)'.
For pronouns, their dative forms (मुझे, तुम्हें, आपको, उसे etc) are equivalent to tacking on the postposition को for nouns.
Therefore, तुम्हें जाना है means 'You have to go' (or 'You want to go')