This is the 15792nd most frequent Polish word.
sądzi
"Thinks" or "judges."
In this sentence, 'sądzi' is used to express Maria's opinion about the book, translated as 'thinks'.
Maria sądzi, że ta książka jest interesująca.
Maria thinks that this book is interesting.
Here, 'sądziłem' is the past tense form meaning 'thought', demonstrating a personal past opinion.
Sądziłem kiedyś, że nauka jest trudna.
I once thought that learning is difficult.
In this sentence, 'sądzisz' is used in the second-person question form, asking someone's opinion.