Here are the best options to fill in the blanks:

1. **for** - "He is best known **for** creating a new art style called Cubism..."

2. **from** - "This was very different **from** traditional art..."

3. **styles** - "Picasso had many different **styles** throughout his life..."

The completed text would read:

"Pablo Picasso was a famous Spanish artist, born in 1881. He is best known **for** creating a new art style called Cubism, where he used shapes like squares and triangles to show people, animals, and objects from different angles at the same time. This was very different **from** traditional art, and it changed the way people looked at painting. Picasso had many different **styles** throughout his life. In his 'Blue Period,' he painted sad scenes using mostly blue colours."