It means: make every effort to know all the words in the world and make up your mind to read all the books in the world.
Extended data:
This sentence comes from an allusion:
According to legend, Su Dongpo was conceited when he was young and loved reading. On one occasion, he wrote a pair of Spring Festival couplets and wrote them on the door:
"Know all the words in the world; Read all the books on the earth. "
Later, an old man showed him a book. He didn't know a word, and his face flushed with embarrassment. He quickly changed the couplet to "I am determined to read all the books in the world" to encourage myself.
Su Dongpo realized that there is endless learning in the world, so he changed the couplet to:
"Try to know all the words in the world; Determined to read all the books on earth. "
This story tells us that there is no end to learning.