Kafka in all his books discusses the anxieties for the modern man, that is the stress to provide for oneself and for one's family, coupled by the monotony of daily life setting off to do the same day after day and trying to cope with life's stresses particularly work and living in the wider community.
In The Trial he extends this theme to the individual who has been singled out to be on trial for an unknown offence they have not committed, and finding themselves alone in their struggle to find a way out which they know from the outset is a complete dead end. One can make the analogy of the individual in a community be it neighbourhood, work, wider family, etc., who for no good reason than perhaps being different in some way, is put on trial indefinitely by that community and has to suffer as a result, with no recourse at ending that 'trial' however much they try.