If they stay away from people, how do they tell them about God or help them in any way? They could pray for people, but they don’t know enough about their lives to know what to pray about..
They don’t have to know the particulars. God knows.
That is an excellent question! Cloistered nuns pray for all people. They don't need to know about their lives. They ask God to provide them with whatever it is that He recognizes they need. All prayers are answered. The best prayers are those of strangers who seek only to ask our Lord to watch over us and guide us to eternal life with Him in heaven.
they get requests for prayers, and usually cloistered nuns have one who sees visitors requesting prayers.
But it all depends if you believe in the power of prayer.
I remember visiting Assisi, and having a Swedish lady mocking the Poor Clares there for “doing nothing”...yet later I found out that they had hidden Jews inside the convent, at risk of their lives, during the war...
I think that we imagine that the celibate and cloistered retreat from the conflicts of our lives.
I'd like to suggest that they confront them without the distractions that are so convenient for us "in the world."
First, anybody who has spent serious time in prayer knows that all the demons mount an assault on those who pray. Lust and competitiveness are just the lightweights. Anger, envy, pride come in the second wave. They fight long, and their weapons are envenomed.
It may well be the the cloistered know our enemies better than we "in the world" do.
Further: Our Lord taught us to pray, "Thy will be done." There must be some good in praying that, even though it is certain that in the final analysis God's will will indeed have been done.
Even if the sisters have not experienced waking up beside the malodorous, whiskered, and snoring brute who drunkenly forced himself on the sanctuary of their bodies last evening, their self oblation may still be one of the tools God graciously uses to save the world.
God knows all needs, and the nuns understand this. I suspect, though, that they keep a Prayer Request list, sent by folks who know the sisters will pray for them, by name, if asked.