"The hours seemed like Mama's never ending ball of thread unwinding in front of them."When the author wrote this he meant that to Esperanza the train ride felt very long.It also meant that Esperanza felt like the train ride was never going to end
" Those roses had known Papa she thought."This means that the roses were there when Papa was still alive. Also, this meant that the roses were Papa's and that they had been touched by Papa.
"For the thousandth time she wiped the tears that slipped down her face."This means that she had wiped the tears from her face so many times. To her it felt like she had done it a thousand times.