Meaning of the word "school of hard knocks" in English

What does "school of hard knocks" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

school of hard knocks

US /skuːl əv hɑːrd nɑks/
UK /skuːl əv hɑːd nɒks/
"school of hard knocks" picture

Idiom

the education one gets from life's difficulties and challenges, rather than from formal schooling

Example:
He didn't go to college, but he got his education in the school of hard knocks.
After years of working odd jobs, she graduated from the school of hard knocks with a lot of practical wisdom.