The Latter-day Saint Gospel Topics page summarizes a patriarchal blessing this way.

Quote, every worthy baptized member is entitled to and should receive a patriarchal blessing,

which provides inspired direction from the Lord.

Patriarchal blessings include a declaration of a person's lineage in the House of Israel

and contain personal counsel from the Lord.

I received my own patriarchal blessing when I was 18 years old.

I was getting ready to head to college and was at somewhat of a crossroads in my life.

I was always a good-hearted kid and I cared about people,

although I was super competitive and had a temper that could sometimes compromise that disposition.

At times, admittedly, I was more concerned with being cool than I was with being kind.

I went to church every week, seminary each day, and home teaching with my dad each month,

but I cared more about being an all-state basketball player than being an all-state priesthood servant.

There was a pull, however, for me to serve a mission.

I needed divine direction before I left home, and I needed to figure out who I really was,

so I scheduled my patriarchal blessing.

The patriarch didn't talk to me much before he blessed me, and I had never met him before.

He pulled over a hard brown chair from the kitchen and asked me to sit in it.

He laid his old, wrinkled hands on my head, and spoke my full name, Anthony Ross Sweat.

And then he began to speak things about Anthony Ross Sweat that I had never conceived.

I felt power.

It flowed from his mouth through his hands into my mind and lodged in my heart, returning out my eyes.

I tried to hold it back, but tears came.

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