Short answers, pulled from the story.
A chantry is an ecclesiastical term with two related meanings: a chantry service, consisting of the Requiem Mass and Office of the Dead sung for the soul of a deceased person, and a chantry chapel, a dedicated space within a church or on private land where those services were performed. The purpose was to help atone for the sins of the deceased and assist the soul in obtaining eternal peace.
The word chantry derives from the Old French chanter and the Latin cantare, both meaning "to sing." The medieval Latin derivative cantaria means "licence to sing mass." The French term for the equivalent institution is chapellenie, meaning chaplaincy.
Richard FitzReiner, Sheriff of the City of London, endowed the first recorded perpetual mass in non-royal society through his last testament of 1191, establishing it in his private chapel at his manor of Broad Colney in Hertfordshire. The chantry was operational by 1212. King Henry II made earlier royal-level foundations in the 1180s at Rouen Cathedral for the soul of his son Henry the Young King.
Parliament passed the first Abolition of Chantries Act in 1545, declaring chantry lands to be misapplied funds and transferring them to the Crown to help finance the war with France. A second Act in 1547, signed by King Edward VI, ended 2,374 chantries and guild chapels and seized their assets.
The 1547 Act required the Crown to guarantee pensions to all chantry priests displaced by the legislation. Many of the priests had previously provided education to urban poor and rural communities; their displacement sharply reduced access to schooling across England.
Katherine, Lady Berkeley, founded the first chantry school in 1384. Chantry priests, because they were not required to offer public masses, had time to serve their communities as teachers, and some of the dissolved chantries were later converted into grammar schools named after King Edward VI.