This is the 86th most frequent Hebrew word.
שהם
The Hebrew word "שהם" translates to "that they are" or refers to a biblical gemstone (shoham). The meaning depends on context.
In this context, "שהם" means "that they," referring to the subject performing the action of reading the books.
הספרים שהם קוראים מעניינים מאוד.
The books that they are reading are very interesting.
Here, "שהם" means "that they," introducing a clause explaining the reason for their pride.
הילדים שלי גאים שהם הצליחו במבחן.
My children are proud that they succeeded in the test.
"שהם" here acts as "that they," connecting the soldiers' confidence to their belief in completing the mission.