"to have time on your hands"
a period of time when you have nothing that you have to do.
a period of idle time.
Synonyms: break, breather, dawdle, dilly-dally, free, freedom, halt, idle, idleness, inactivity, indolence, interim, interlude, intermission, laze, lazing, lazy, leisure, letup, loaf, loafing, lull, pause, recess, repose, respite, rest, spare, suspension
a lot of time on her hands
therefore she has spare time to relax and read ...