en_tn/act/01/20.md

Peter continues his speech to the believers that he began in Acts 1:15.

For it is written in the book of Psalms

Based on the situation with Judas that he just recounted, Peter is recalling a passage in the book of Psalms that he believes relates to the current situation.

the book of Psalms

This can be translated as "the book of Hymns" or "the book of Songs." This book is part of the Scriptures.

Let his field be made desolate

A property falling apart and overgrown suggests the owner is dead.

And do not let even one person live there

The land is unclean (taboo) or is unfit to live on.

let someone else take his position of leadership

"may he be replaced in his leadership position"