A general statement about the main purpose of monastic life?

I will give the true spiritual purpose as well as practical purposes. Here I am specifically refering to Western Monasticism. Eastern monasticism could be entirely different

the main purpose of the monk is to praise God unceasingly through the Liturgy. it is born out of the sole desire deep within the heart of the monk to serve and love God. this desire is so strong that the monk leaves everything behind and gives his life as a gift to God for the glory and praise of the one he loves. Specifically the monk praises God through the Liturgy.

Depending on the order, the monk gathers 7 times a day with his brother monks to recite the Divine Office. This is the also referred to as the Liturgy of the Hours. The Divine office is the official prayer of the Church, it is the mystical body of Christ, the Church offering praise to God the Father through his Son. The life of the monk is one of prayer. Specifically and ultimately a prayer of praise to God.

The monk also prays for the universal church and for members of this church, in other Words, for all mankind. He endures suffering and trials, and the hardships that come along with living such a rigorous life. But the suffering is entirely offered up in union with Christ' suffering for the good of all mankind.

The practical purposes vary and depend on each monastery. Some monasteries run prep-schools, colleges, seminaries. some monasteries run retreat houses. some monasteries send their monks to work in local parishes where there is a shortage of priests. And there are some monasteries that only do work which contributes to the self-sufficiency of the monastery. it just depends.

primarily, however, to sum it up, the purpose of the monks life is to give his entire life as an offering to God for the purpose of praising God and giving the glory to God which he deserves.