What are the four marks of the Church, and how did DLS embody those marks?

The four marks of the Church are one, holy, catholic, and apostolic.
According to Catholic doctrine, "one" means that the church worships one God and is made up of one faith. Just as Jesus Christ, the Father, and the Holy Spirit are one, the church is one body under God. The church is also considered holy in the sense that it is a spiritually cleansing medium: since God is the head of the church, He makes holy all who continue to worship Him. The holiness of the church is then manifest in its holy works on behalf of the world.
The church is also considered catholic in that it is universal in its mission: to proclaim Christ to the world for the salvation of all. Last, but not least, the Catholic Church is considered an apostolic church. This means that its religious traditions originate from the apostles of Christ. The Church considers the pope and the bishops natural successors of the apostolic traditions.
If by DSL you mean St. John Baptist de La Salle, the same is known as the founder of the Brothers of the Christian Schools. De La Salle is also recognized today as the patron saint of Christian teachers. How de La Salle embodied the four marks of the Church:
through a merging of secular and religious education, he made education available to all. De La Salle structured education as an inclusive and universal experience.
through religious instruction, de La Salle promoted civic responsibility and the Christian spirit. This type of instruction reinforced the Catholic Church as an instrument of holiness.
De La Salle's schools also recognized the apostolic tradition: it trained new priests and lay teachers to teach the people.
through La Salle's "Simultaneous Method," students learned under the direction of one teacher. This is the principle of "one": a teacher reads aloud to the class, while each student follows silently. As the church is one body under Christ, the students are one body under the tutelage of a teacher.
 
https://www.lasalle.org/en/lasallian-holiness/st-john-baptist-de-la-salle/

https://www.loyolapress.com/our-catholic-faith/scripture-and-tradition/catholic-basics/catholic-beliefs-and-practices/marks-of-the-church

https://www.newfoundations.com/GALLERY/LaSalle.html