The new motto proprio from Pope Francis, is a papal declaration establishing new canons (regulations) for the determination of whether a sacramental marriage exists in cases that are brought before the local Church.
Nothing has changed regarding the teaching of the Church about the indissolubility of a sacramental marriage. What has changed is that many cases which have resulted in a clear declaration of nullity will not have to be appealed to a court in Rome automatically. Those cases that need to be appealed will still be sent for a second opinion but in many, if not most cases, the decision of the local or diocesan tribunal will be fair, final and relatively fast.
Secondly, the recommendation is that the costs of the process for a declaration of nullity should be kept down. In the case of those with limited resources, especially in many poor Catholic countries, these costs should be provided for by the Church as a matter of pastoral concern. The Archdiocese of Toronto makes a point of not burdening people with the costs while accepting donations for the time and expense of dealing with cases from those who can afford to contribute. The principle is that no one should be denied a hearing because they cannot afford it.
By putting the emphasis on mercy and fairness while upholding the sanctity of marriage and a high degree of canonical clarity, the Church will help many more people to regularize their lives, giving them hope and allowing them to be strengthened by the sacraments in their journey of faith.