This is the 67th most frequent Hebrew word.
לה
"To her" or "for her."
In this sentence, 'לה' (la) is used as a pronoun meaning 'to her', showing to whom the gift was given.
נתתי לה מתנה לחג.
I gave her a gift for the holiday.
Here, 'לה' (la) indicates possession, translating to 'she has', implying ownership of the books.
יש לה הרבה ספרים.
She has many books.
In this case, 'לה' (la) indicates the recipient of the action, meaning 'to her', specifying for whom the song will be sung.