This is the 617th most frequent Greek word.
κάνοντας
"Κάνοντας" means "doing" in English.
In this sentence, "κάνοντας" (doing/making) shows simultaneous action to the main verb, "Διάβαζε" (She was reading), indicating what she was doing while reading.
Διάβαζε το βιβλίο, κάνοντας σημειώσεις στο τετράδιο.
She was reading the book, taking notes in her notebook.
Here, "κάνοντας" illustrates a concurrent action to the main event, "Περπατούσε" (He was walking), specifying what he was doing during that action.
Περπατούσε στον δρόμο, κάνοντας ένα τηλεφώνημα.
He was walking on the street, making a phone call.
In this usage, "κάνοντας" implies the means or method through which the main action "Έμαθε" (She learned) was achieved.