This is the 3482nd most frequent Russian word.
прочитать
To read through or finish reading.
Here "прочитал" is used to indicate that the action of reading the book is completed and refers to a past accomplishment.
Я прочитал эту книгу за неделю.
I read this book in a week.
In this sentence, "прочитайте" is used in the imperative mood to give a polite command or instruction.
Прочитайте в голос следующий абзац.
Read the next paragraph aloud.
Here "прочитать" is used in the infinitive form to indicate the intention to complete the action of reading.